I play the same a lot of the time. Like ur 4bet sizing. Against ppl w/ very low ftcb stats and high AF I may b/c half pot on the flop, but without this info I think checking back and folding turn is good. There are arguments that checking back the flop can induce turn spew, but the flop whacks our p/f 4b range. Dont think villain has any air in his range after 3b"n an utg raiser and flatting a 4b.