Just bet flop, no reason to think that you should play any kind of 'defensive' there. You are within a range advantage as preflop 3bettor, and your hand has a lot of good qualities to just put money right away on the flop. And you also have a lot of incentive to put money there, as folding just any random two overcards is really great deal for not-yet-improved QJhigh.

Then, as played i would also use same logic OTT.

Not sure what 10NL fish is doing but when you 3bet 4.5x from SB a lot of people will fold 22-55 close to 100% and maybe even some 66 will fold for tighter players so you can treat the flop as if the flop is like 226 or something.

Even if CO has all 22-66 it's probably still just a high frequency flop cbet spot and then play more carefully from the turn onwards. 200bb+ deep it's more reasons to be trying to doge stacking off vs sets,

Just ran some sims at GTO+ and CB'ing in a high freq with a 0.33psb is good. Since the defender is IP, the solver almost went to a 0 to 1% raising frequency, but I don't believe this will occur in a real situation. Also, I tried to invert and put your range IP and his range OOP, and again using only a 0.33psb CB the solver resulted in a 15+% raising frequency, which means that positions are really valuable.

Assuming that GTO+ likes to raise more often when OOP, is a good idea to check our entire range on this flop and be aggressive vs stabs?
Also, ran a sim of 100% checking range and the preflop caller goes for 22% 0.5psb stab, which I believe would be bigger in a real situation, the solver resulted in a 10% XRaising freq. Then I node locked to somewhat 45% stab freq, including overpairs, top pairs, flushdraws, some OESD, etc. The X/Raising range went to almost 30% frequency.