5/10 river decision, set

[setzf]

I agree that the limp isn't standard, only because in my opinion there isn't necessarily a standard play for 88 utg. Raising v. calling would be dependent on the table and your image.
I think you definitely have a 3 bet here against most bad online players. If he is limping with big pairs that tells me he doesn't understand hand values well and is only thinking about what he has and not what you have. A "donk", as you describe him will virtually never fold two pair or a set here and a donk who only think about his own cards will raise a lot of 2 pair hands here. Without a solid read I'm not folding to a cap in a low limit game i feel.