villain is 24/11. If I know he's incapable of 3barrel bluffing, and will only bet KQ+ on this river,
should I be donking? Like 26 to get value from Ahi, Jx, and weaker pairs.

obviously this will increase his bluffing frequency, which puts us in a tough spot because we don't have the reads to rely on anything but timing/sizing/feel.
I'm fine with this and feel like we should be betting here.

Maybe I'm just overcomplicating these hands vs abc fish, but it feels so weak checking here when I know he'll check back like 95%+ of the time and I crush his range.

Hm I agree this is an annoying spot. It seems like the best solution is to have lead turn? Villain is never folding a jack and you can probably get another street on the river. Raising turn seems to put maximum pressure on him if he has Jx or some midpair like TT that he's confused with.

Calling turn and donking river probably would work, but it doesn't seem like "good poker", more of a hack that will probably work okay here.

edit: as a side note I would always 3bet this pre, and I usually never float OOP like this. Generally I'd prefer a more brute flop c/r with my overcards since you get into a lot of weird spots later.

some obvious but important stuff:
u may crush his check behind range, but it may not be so against his calling range
also you are oop, extracting value is supposed to be harder
i don't have an answer to your q per se, but betting small on the river to get some small value against a J seems like a good idea but i think c/r the turn is such a better play esp if what you say about him only vbetting KQ+ on the river