Thanks all for responding.. waited a little to see more responses coming out. Thanks again.

The flat pre... My range will be very well disguised and nobody argues for the blinds and there stack sizes. Didnt mention the fact that the blinds and plyr behind are competent plyrs (mostly in s500. so just assumed ppl would assume this as the stndrd..... + fwiw, competent doesnt mean good or sicko. just know and read ranges..).

I like my flat here because it will not be perceived as a lot of strength flatting such a spewy villain IP given these stack sizes.. I would say i 3b 70% and flat 30% of the time, in this spot.

Flop raise, was thinking about it, like it a lot as well tbh. esp to balance to other flop raises I often do. Think its probably a nicer line and gets a lot of action.

Turn..... I think sucks the hardest. What hands do I flat pre that flat turn again...
Same goes for what his betting range is on the turn; AJ QT TJ KQ KT AT AQ XXhh Ahx JJ Jx
Our range on the turn after we flat can still be wide enough (not sure how he views me) as AK some %, KQ AJ AhQx QhJx JhQx

On the river we hit about the best card in the deck for us, yet he bets so hard.. The Q here is, what range bets so hard on the turn, that bets so extremely hard on the river.
Thats where im the most confused. However, depending on how he views me, my turn call range is pretty tight and the K might even give me a hand I can now call with instead of fold would it have been a blank.

However, if he holds Nutflush or AJ and I call his bet, it doesnt matter if its 10K or 20K on the river, if I call, he wins there 95% of the time. This makes his sizing a lot of sense.
However, I can shove and make him fold those hands, repping only KK, KQ and QQ, which is good since we have the K blocker and on the turn our range is very narrow and no further draws really missed..
It will be very hard/though for him to hero call AJ or a flush here. Since hes a very spewy (but good) HU player, I think he's definitely capable of folding river there with those hands.

I ended up folding because I was just totally lost with the sizing's on turn and river.

I like the flat pre given the stacks of the BTN/SB/BB.

Fold turn. This board smacks your percieved range and he continues to bet. If you were villain what hand would you expect to fold OTT that called the flop? I can't think of any.

Oh.