Sounds tough, and 6max I'm also not very sure about. But a few thoughts anyway.

Maybe play really tight OOP and much looser with position--i.e., not check-raising thin draws OOP but just laying down and CRing big hands.

Then with position maybe call on some thin draws with a clear view to what else the board offers (like what we've been talking about on several hands). Like, call with good flush draw only if you have some chances of bluffing a straight on a tough board--and if they bet the straight but you consider it dodgy whether or not they have it, then be willing to raise with your flush draw as backup plan.

While I have limited SH experience, I've had pretty decent luck by still playing quite tight (maybe like VPIP 30% or so, particularly when they're constantly raising) and also using that tight image to make selective bluffs.