One theme we read frequently here is that some/many Founders thought that "reason trumps revelation". This is, of course, prima facie absurd. Once you take it seriously, it must be false.
Think about it: you have access to real revelation, with no cause for doubt. To papaphrase an old chestnut, who you gonna believe, God or your lying reason? If God is speaking to you, and you know that it really is God, you would listen. So would the Founders.
The problem is not reason vs. revelation, the problem is epistemic: how do I know that this particular teaching is revelation? For the old-school paleo-orthodox, this is no problem: you have the authority of the Church to lean on, with their learned fathers and their deep discernment of what writings were inspired and belong in a biblical canon.
But if you are an American protestant of the revolutionary era, whether neo-orthodox or not, you have tossed the Church and its learned clergy out the window, so the epistemic probem is real for you: you are still willing to believe God over anything else, but how can you tell what is truly from God?
The enlightenment answer is that the Word of God has inherent authority. It is so wise, so sublime, so obviously true, that it is self-revelatory: the true Word of God is like a light shining in textual darkness, and your reason is the God-given faculty that gives you the power to respond to that Word.
In a nutshell, for the Founders and their generation of American protestants, reason does not trump revelation, reason discerns (and then submits to) revelation.