PLO10 vs turn check/raise

I'm not sure how many combos of 55xx he can check/call on the flop with. Probably only something like A355, AK55, unless you think he's peeling very loose OOP. He could also definitely have AAxx here that didn't want to inflate the pot OOP. He could conceivably c/c on the flop given how dry the board is.

From his stats (playing 82% preflop), we can expect him to call with hands like 2345, A246, etc. we can also expect him to call on the flop with these hands.

On the turn, I'm not sure that he plays all of his 55xx combos this aggressively (he doesn't seen particularly aggressive from his stats). I would be surprised if he's playing like this with draws like AK67. Guys like this will often play small sets/weakish draws passively particularly out of position.

As a result, I would weight his range to straights sometimes AAxx (say 50%), sometimes 55xx (say 50%) and occassionally draws (say 25%):

ProPokerTools Omaha Hi Simulation
600,000 trials (Randomized)
board: 8♣A♦3♥5♠
889T 35.70% (214,190 wins, 0 ties)
AA**@50,24**@100,55**@50,67**@25 64.30% (385,810 wins, 0 ties)

Against this weighted range you have 35% equity.

The only draw hits on the turn and you get checkraised.

Well that sucks doesn't it?

Your turn bet is big enough that villain knows you're not bluffing here. I doubt this could ever be a bluffraise so we have to consider what his value raising range is of hands that call the flop bet.

It does look like you're going to be behind a lot of the time here.
First of all what's your own aggression like? If you're pretty tight I can't see this being anything other than the nuts, but if you have been barrelling a lot then you probably have to stack off at this point.

When faced with marginal plays, I tend to default to calling as it stops you from being exploited in the future if opponents know you make big laydowns.