The default here, should be to 3bet preflop to 10-12BB or so. You
could just flat pre, but that's really just better if you know villain will fold a ton preflop; and in that case, you're better off 3bet-bluffing more.
I'd much rather raise the flop than flat here. If the flop donk is TP or a smaller overpair, he's probably not folding to a raise and we're almost always ahead of UTG when he just flats this tiny donk bet. Raise flop to .50 and continue from there.
As played on the flop, just bet the turn for .60-.70 for value.
River call is fine, but you're gonna be beaten here more often than not (but not often enough to fold, though)