> I may experiement with heating my bear vault and reshaping it a little bit.

Try heating a plastic water bottle first. You might be surprised how quickly it shrinks! I doubt you would have a good result heating the BearVault.

I put my BV inside the pack vertically, but first I fan-fold my Thermarest Neoair mattress so it is between my back and the canister. Add clothing around the canister, then ...inflate the air mattress.   No more pressure points! cool