I don't see how flatting can be too bad. We'll be in position and will have the best hand a lot of the times. The stack sizes behind don't look like rejam sizes so I wouldn't worry too much about being rejam squeezed.

Squeezing to try and get heads up is ok but we might end up in a tough spot if UTG 4-bets. In that case we probably have to fold and won't be able to realize our equity.

All true, am actually more concerned about reg in +1s flat

I prefer to flat with hands like A2s+, suited connectors and stuff like that. With 57 bb's I would raise to something like 9k just like you did and doing a cbet in almost every flop.

3-bet to 20k ..even with no stat reads this is a premium hand that should be protected

3bet to protect your hand and to hopefully get headsup postflop! Easier to play the hand postflop also after 3betting.

Typical example of a situation where having some sort of a read on player ranges is important...in absence of any data i would prefer flatting here and seeing the flop in position .