[einbert]

I don't see why just three-betting the flop isn't the best option. If it's capped you have a relatively easy turn check/fold, if not you can keep firing and folding to a raise.

Do you think it's very likely that MP1 will cap the flop with AJ? I don't think many players threebet that hand PF in the first place, so I think it's either JJ-AA or AK and I doubt AK is capping the flop but wouldn't be at all surprised to see it raise the flop up.

I really doubt an overpair is raising you on the river, I imagine they would either call down, cap the flop, or raise the turn. If you get to the river against an overpair they are going to just call almost every time I believe.