Some time back I published three essays, originally written to a friend who was working over the concept of how man knows. He replied, and this is my response to his reply. I lack the time to reshape it into person-neutral essay, so it retains its epistolary format.
Thank you for your diligence in attending to your argument. I can only apologize for the delay which preceded this response. As ever, Christ's brothers must seek to "let all things be done for building up", and so my prayer for you, your family, and myself, is that we may "all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ".
I first address the footing of the argument, which I think to be substantively summed up in your subject line: "Is Truth Analogical?" In short, no. If this is your understanding of my position, I am afraid I have conveyed it badly. My position is thus: Truth is absolute. Human apprehension of truth is analogical.
A Biblical Survey of Truth
Truth exists because God exists. Jesus is "the way, and the truth, and the life", and to follow your John 17:17 argument with another link, God's Word is truth, and Jesus is the Word, and Jesus is God, therefore it is completely consistent to claim that God himself is truth. Truth bears that name by correct association with God. If God has said something, it is true. If God has done something, it was done truthfully, not deceitfully.
I accept your definition of propositional truth and falsehood, but I assert that it is insufficient, and I stridently disagree with your sentences "All truth is propositional. All falsehood is propositional. Only propositions may be true or false." In addition to being a quality of propositions, truth is an attribute of God, and is an attribute of God's people. Consider the following:
John 8:43-44 - Why do you not understand what I say? It is because you cannot bear to hear my word. You are of your father the devil, and your will is to do your father's desires. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies.
James 2:19 - You believe that God is one; you do well. Even the demons believe—and shudder!
Satan (and the demons generally) possess true propositions, yet Satan has no truth in him. Therefore, I am led to assert that true propositions do not sufficiently constitute a concept of the truth. There is further support for this position:
Rev. 19:11 - Then I saw heaven opened, and behold, a white horse! The one sitting on it is called Faithful and True, and in righteousness he judges and makes war.
Rom. 3:4 - Let God be true though every one were a liar, as it is written, “That you may be justified in your words, and prevail when you are judged.”
John 1:14-18 - And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. (John bore witness about him, and cried out, “This was he of whom I said, ‘He who comes after me ranks before me, because he was before me.’”) For from his fullness we have all received, grace upon grace. For the law was given through Moses; grace and truth came through Jesus Christ. No one has ever seen God; the only God, who is at the Father's side, he has made him known.
Truth is a quality, but not just of propositions; it is a quality of our God, of His Son, and of His people (who are obviously imperfect in it, but will be perfected in it when we see Christ as He is).
Christ Jesus came into the world as truth incarnate and personified. That is the point of John's message on truth. Since Jesus is God incarnate, He is truth incarnate. John 1 is a creation-invocation passage, equating the locutionary establishment of the world with the Son of God becoming flesh, which is another fiat-creation act announcing the final re-creation which would be effected by this God-man. John is not into propositions, as far as I can tell, but he is deeply concerned with our apprehension of Christ's deity and the consequent power of the salvation He brings.
On Propositions as They Relate to God, Man, and Truth
To hedge against error, we must maintain that while God is wholly true, true propositions are not the whole of God. Satan is not participating in godhead when he says that God is one. We are not participating in the godhead when we speak true propositions.
Propositions are the human language of truth. Language is inherently analogical, just look at any primer. There are pictures and words, pictures and words. The language must be linked to a real thing in order to have meaning. Is the true cat the sequence of glyphs on a page, or the furry quadruped feline that man has had a love-hate relationship with for millennia? There is no escaping the language-is-analogy trap if you are just a human. This is where modern academic scholarship resides, and it is a morass.
God, who is the truth itself, can speak locutionarily, and can make His words mean what they mean. Thus, I assert that truth exists as a correct relationship between the object in question and God, the truth-giver. A cat is a cat because God made it so, and gave Adam the prerogative of naming it. It seems that the dominion mandate is the ground of man's ability to make and use language, but man's language is ever bound to conform to God's words and works if we wish to call our speech "true".
I must also disagree with you on the communication of knowledge. You assert (via quotation) that "Knowledge can only come through propositions." I must take issue with this on the basis of Scripture. Consider:
Jer. 31:33-34 - For this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the LORD,’ for they shall all know me, from the least of them to the greatest, declares the LORD. For I will forgive their iniquity, and I will remember their sin no more.”
God promises a day when teaching (the systematic communication of propositions) will cease! How can that be, if all truth is propositional and may only be communicated via propositions? The answer comes from John:
1 Jn. 3:1-2 - See what kind of love the Father has given to us, that we should be called children of God; and so we are. The reason why the world does not know us is that it did not know him. Beloved, we are God's children now, and what we will be has not yet appeared; but we know that when he appears we shall be like him, because we shall see him as he is.
The advent of Jesus Christ in glory will cause every knee to bow and every tongue confess that Jesus is Lord to the glory of God the Father, but such assent to propositions will not save the reprobate. And the elect, though "now we see in a mirror dimly, but then face to face. Now I know in part; then I shall know fully, even as I have been fully known." Full knowledge (a concept that seems like it must be equated with Godhead in the Clarkian view) is the result of the face-to-face encounter with the glorified Christ on the last day. A bodily experience bestows knowledge. I consider this sufficient Biblical evidence to reject the proposition-only view of imparting knowledge, but more evidence is available.     The locutionary acts of God are further examples of God making truth via His word, the statement creating the truth it speaks. 
You rightfully express the concern that a rejection of exclusive-propositionalism and an acceptance of the analogical view might sunder man from his Creator, barring access because of a difference in kind. However, I have in no wise excluded from God the knowledge of all true propositions, I have merely stated that this is an insufficient (and unbiblical) view of God's knowledge (a view better suited to pagan philosophers who like unmoved movers and such). God knows all things, including all true propositions (which function as the human language of truth), and we know some true propositions. Therefore, we do know some of the things which are in God's mind. To assert, however, that we know as God knows is false, because propositions are not a sufficient definition of knowledge. We know some of the things that God knows, but to claim equality in knowledge is presumption. In short, the analogical view is not contradictory, while the pure-proposition view is not Biblical.
Let us move on to your syllogisms. I fully agree with the first, and accept the conclusion that all Christians are thinkers of true propositions. In the prior paragraph I have, in a way, agreed with the first premise of Argument 2 - All true propositions are God's thoughts. I do not even find fault with your conclusion (All Christians are thinkers of God's thoughts), but you make an underlying assumption, which is unstated. If I were to rephrase the first premise of the second argument as I understand you to maintain it, it would read: All true propositions are THE ENITRETY of God's thoughts. To this I object, as discussed in the first three pages.
Nature, Language, and Analogy
Onward to your informal argument. You qualify "knowledge" with the terms "human" and "God's", which I think is entirely appropriate, because those ownership-adjectives qualify the word that follows them. Human knowledge is limited by our nature (and I know you reckon with limitations of nature, or you would not be a Calvinist). God's knowledge is limited by His nature (ie- it is perfect, self-consistent, complete, and essentially unitary). In order to ease commerce between these, there ought to be a language, and that language is propositional truth (note that I observe Biblically-documented exceptions to propositions as the conveyor of true knowledge, but I allow those to be indeed exceptional). But note, commerce between God and man is condescension on God's part; He spoke first, we spoke because spoken to.
To return briefly to the concept of language, you require terms to be univocal in order for truth to be preserved in communication. This places a burden on language that it cannot bear. Only God can bear the burden of univocity, which He does when He speaks, acts, or makes man to know that which He wishes man to know.
You assert (via a quotation) that "An analogy of the truth is simply not the truth." This is false, and I point you to the Psalms, and take as an archetypical example:
Psalm 61:2b-4 - from the end of the earth I call to you
when my heart is faint.
Lead me to the rock
that is higher than I,
for you have been my refuge,
a strong tower against the enemy.
Let me dwell in your tent forever!
Let me take refuge under the shelter of your wings! Selah
Is it true that God is a tower? Well, yes, because we hold a very high view of inspiration, but how is God a tower? He is LIKE a tower in His defense of His children, the security and might of His power, and His exaltation over all around Him. Is God a bird? Well, He is LIKE a bird, in His comforting protection and care of His own. Do Psalms like this inform our true knowledge of God? Absolutely! But they do it via analogy. If you wish to explore this more, see the references.
The Meeting of the Minds
Where does all of this lead? I hope to have demonstrated 1) the Biblical idea of truth and knowledge as inclusive of, but not exclusively composed of, propositions, 2) that the language from which you demand univocity is a shifting sand unless God orders it, which He does via the dominion mandate and revelation, and 3) that the analogical view of knowledge is not contradictory, but in fact accounts better for Biblical data. But these are not the heart of the matter.
John 8:31-38 - So Jesus said to the Jews who had believed him, “If you abide in my word, you are truly my disciples, and you will know the truth, and the truth will set you free.” They answered him, “We are offspring of Abraham and have never been enslaved to anyone. How is it that you say, ‘You will become free’?”
Jesus answered them, “Truly, truly, I say to you, everyone who practices sin is a slave to sin. The slave does not remain in the house forever; the son remains forever. So if the Son sets you free, you will be free indeed. I know that you are offspring of Abraham; yet you seek to kill me because my word finds no place in you. I speak of what I have seen with my Father, and you do what you have heard from your father.”
Your last quote from Crampton is well-taken. We do not get an analogy, we do not get a pointer, we get the truth. But the two hinges of this argument are the questions: WHAT is the truth, and HOW do we get the truth?
To the first, Jesus supplies the answer. He, the God-man, born of a virgin, born under the law, He is the truth. That truth is powerful, as John shows in chapter 1. It is the creative-redemptive power of God, lodged forever in the King of Kings and Lord of Lords, Jesus Christ, who will set you free.
To the second question, Jesus again supplies the answer.
John 14:1-11 - “Let not your hearts be troubled. Believe in God; believe also in me. In my Father's house are many rooms. If it were not so, would I have told you that I go to prepare a place for you? And if I go and prepare a place for you, I will come again and will take you to myself, that where I am you may be also. And you know the way to where I am going.” Thomas said to him, “Lord, we do not know where you are going. How can we know the way?” Jesus said to him, “I am the way, and the truth, and the life. No one comes to the Father except through me. If you had known me, you would have known my Father also. From now on you do know him and have seen him.”
Philip said to him, “Lord, show us the Father, and it is enough for us.” Jesus said to him, “Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own authority, but the Father who dwells in me does his works. Believe me that I am in the Father and the Father is in me, or else believe on account of the works themselves.
We know God by believing in Jesus, His Son. We are not just to know facts about God (I appeal to James), we are not just to trust God (I appeal to Mary in John 11:21-27), we are to believe in Jesus. This is the intellectual, moral, emotional, and willful act of lunging after Christ, heedless of whatever may impede. It is not Kierkegaard or Greek Orthodox, because we use our minds. It is not fatalism, because we use our wills. It is not intellectualism, because we use our whole man, all our faculties, to not just apprehend truths about God, but:
Phil. 3:13-14. - Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus.
We are to love the Lord our God with all our heart, mind, soul, and strength. That is the heart of the matter. That is how our God meets us. He calls us, and we answer with all that is in us. "How can we know God aright?" is the greatest question in the world, and the answer is not found in scholastic debates about knowledge, but in Jesus Christ.
I stress the section above because your inquiries into knowledge have ramifications throughout the Christian life. They are bound up with how you understand Christ's person, work, and claims; they affect any view soteriology, Scripture, and God; and they certainly provide ammunition with which to enter firefights with fellow Christians about matters which are difficult, murky, and not central to salvation by grace through faith in Christ.
As you probably know, I am fond of the passage below, and am made fonder because of my own argumentative proclivities:
Phil. 3:15-16 - Let those of us who are mature think this way, and if in anything you think otherwise, God will reveal that also to you. Only let us hold true to what we have attained.
Paul rightly admonishes the churches to hold fast to the truth once for all delivered, and beware of falsely-called knowledge, because real knowledge, true knowledge, builds up the brethren in love. I also urge you to heed the outcome of a life lived quarreling in pursuit of acutely perfect knowledge. The men who chase this will-'o-the-wisp end up outside the church, producing no fruit but sour grapes, and having little or nothing to do with the healthy, hearty Christianity that is prescribed by God. Godliness with contentment is great gain, and any theory or idea that drives you to distraction and damages your participation in the life of the church ought to be recognized by its effects.
Heb. 13:7-8 - Remember your leaders, those who spoke to you the word of God. Consider the outcome of their way of life, and imitate their faith. Jesus Christ is the same yesterday and today and forever.
-----, I urge you to consider these things, study the Scripture before you study men, and to pursue Christ faithfully in His church, for she is His bride, and ought to be adorned with diligent, thoughtful men like yourself. On this issue of analogical knowledge, I have said my piece once and now twice, and I pray it has been faithful to Scripture and respectful to you, but I am ever aware of the warning of Titus 3:10, and wish neither of us to fall under it. You and your family are in my prayers, and I hope to God that our discourse will but strengthen the both of us.
 1 Cor. 14:26 - All quotations are from the ESV
 Eph. 4:13
 John 14:6
 John 1:1
 John 14:10-11
 Isa. 65:16
 1 Jn. 3:2
 Isa. 45:23 (cited Rom. 14:11)
 1 Cor. 13:12
 1 Kings 19:9-13 - Knowledge via experience (God or not-God in the fire, etc.)
 Gen. 28:16 - Knowledge via pictorial dreams
 Ex. 6:6-7 - Knowledge via experience of God's redemptive acts
 Ezek. 29:8-9 - Knowledge via judicial acts
 Ezek. 39:28-29 - Knowledge via a disciplinary act
 Gen. 1
 Ezek. 16:6, Ezek 37:1-14 - Same idea of God giving a command that communicates the reality
 Psalm 3:3; 17:8; 18:2, 10, 30; 33:20; 36:7; 57:1; 59:11; 63:7; 78:65; 84:11; 104:3; 144:2; more available upon request.
 Jude 3
 1 Tim. 6:20-21
 Titus 3:2
 1 Tim. 6:6
Should anyone desire to have the works he quoted to me appended, just say so. Again, in the interest of time I have omitted them.