Yes, as you point out it's tough for him to have many bluffs, and your range is very strong. So I'd be pretty meh facing vilain's river bet. And u say vilain is tight reg, so I wouldn't expect him to bluff too much in general after raising from UTG.
As for earlier streets, I could consider a flop raise but flatting is def very good with reg behind to act.
Turn I find the sizing too big. Your line looks strong just by donking that turn 3way with UTG involved, so when you bet that big you're almost always nutted or at least heavily weighted towards value. I think you're scaring off most weaker hands than yours. So I'd check or bet way smaller.
Because you bet that big OTT, this shall be an argument for folding river.

i think a call is prlly fine here with your hand and his small bet otr like hes giving u a rly good price and you have a pretty strong hand that should be good sometimes here....without looking at the numbers i think calling has gotta be netting a profit here @ 500 to win 2kish?

with my forum tells tho im prty sure you lost this pot lol

lost, he has nut flush A8 diamonds. it is true that pot odds were the main reason i called, but seems like at best im calling to chop with AK, and usually just has a flush

I think this should be a squeeze preflop . it s a big achievement to win the pot preflop with so much money in . The fact that you have a fish in the sb should be a good enough reason for him to open weider then normal . I d make it 280 pre and fold to a 4bet ( you are not geting bluffed here at 5 10 enough almost never , especialy if you have a good image ) . on the river he is not beting worse for value and i can t see any bluffs he can get with at this point ( maybe AdQ but if he turns that into bluff he will bet biger for sure ) . So you are practicaly calling 500 to win 800 (half pot when you chop with ak) . You need around 27 % equity and you have something between 10 and 25 depending how he plays his sets on previous streets , so i think you should fold even you are geting very good odds

i prefer 3b pre w\ AK in the spot, seems great for a squeeze.
but a flat can b fine sometimes if it's that kind of table that when the original calls it snowballs into a 5 way pot.
on flop i much rather raise the sb open, as u said he's a weaker player and u want to iso urself with that kind of player, most of his range consists of a Kx which u r crushing and maybe some fd that u have a big edge over.
flatting flop makes ur hand look very weak and it may encourage ppl behind u to squeeze with a some hands u are ahead of, like Axd, once they do ur hand is either a head by a little or behind by a lot (vs sets) and that kind of an ugly spot to b in, so i think ur hand it too weak to just call and rely on other players weak plays in order to get to SD and take the pot. since u are most likley folding to a double barrle.
so making it 375-425 on the flop is imo the best play since u just flatted this hand.
OTR as played it's very close, could go either way depending on the player but generally i would tend to call that raise given these odds, like u said he shouldnt have any bluffs in that spot, but never rule out the occational brain fart after ur hand is so invisible as played (a thought like "he checked on river when the flush hit, so i can prolly take it now since i floated QQ\KQ\68s\89s on flop and turn and for whatever reason ended here OTR").