Jeffersonian Olympics (CW: Slavery, racism, white supremacy)

[Todd]

I'm coming a bit late to this one so forgive me if I go over similar ground that others have touched on. I don't want to influence my comments by reading the others yet. I've written some poems in form but most in free verse so you or others may have a more trained ear. I tend to focus on content first and form second.

“Jeffersonian Gymnastics”

We hold these truths to be self-evident:--This is a nice callback opening to his own writings and his own likely cognitive dissonance (at least to some extent).
That Colored folk lack our white endowment. --endowment is okay, but it reads like a financial sort of feel. They lack our assets. So, it's a word implying advantage where I think you may want to slip into more superiority like (preeminence which at best is a slant rhyme. though you're likely stuck there because self-evident probably doesn't have a pure rhyme option). 
Inferior in body and in mind,
Best housed apart, as Nature has assigned.--You had designed here before which is probably better because assigned seems to lessen agency (like society has assigned and Jefferson despite the contradictions seemed to be pushing to change that assignment even if that meant freeing and then deporting). When you invoke Nature though or natural law it's an appeal to design or creation. 
Liberty's tree is washed in tyrants’ blood,
While slaves bear lashes, as before the Flood.--this seems like an end word for the point of rhyme. I'm just having trouble seeing an Antediluvian callback. Moses and Egypt maybe, Pre-Noah as Jefferson would have understood it isn't clicking for me.

Though I proclaim all men to be my equal,
Yet my own children are dark, skin like treacle.--This couplet feels like the meter is irregular. Also, I'm not liking the syntax of this line. I'd love treacle but I'd like this to read more smoothly.
I tremble, for God may be stern and just,--do you get a sense that Jefferson held to a Jonathan Edwards type God, or did he lean into mercy more. I believe the wink line but I'm not sure about this one.
Yet trust He’ll wink at my familiar lust.
They share my blood, but not my soul nor name;
I claim their flesh, unmoved by guilt or shame.

Some say I preach liberty whilst holding chains,
But they just lack my noble white man’s brains.--This lines are more obvious than your others. There's no irony or nuance and I think you can elevate this even if the message is the same (it's mostly word choice. Also, this is implying that Jefferson's critics are the slaves themselves and if that's the case he already has said they are inferior in mind. These are probably his abolitionist critics.
They say my words were light, my deeds were darkness,--I don't like light/darkness it feels again like forcing syntax for the rhyme.
That I sold fellow men in labour's harness.--I like labour's harness and the implication of a livestock view.
Freedom spoke through me; The voice of others?
Bought by the silence of my brothers.

In Fate's book it is writ, "men must be freed"--What is fate's book?
But let my chattel work, or let them bleed.

Hopefully some of that was helpful.

Best,

Todd