It’s worth experimenting, although I do suggest that you take a look at the various vat construction threads on buildyourownsla.com, there are threads there covering vat designs and various sprays. You’ll probably find a more active DIY vat community there. I think there’s a fair chance that FEP without the soft layer will reduce the PSP’s flex-release capabilities to a sufficient degree that it could be difficult to print larger items.
I actually feel that well performing vats might be better done going in the opposite direction. Rather than going for an immortal vat made out of the toughest materials, to rather make a really cheap and disposable vat like:
http://www.2engineers.com/shop/vat-for-resin/
where you can always start fresh. The complex behavior and clarity we need from vats makes me think of contact lenses, where convenience and quality are had not by making a supertough indestructable lens, but rather my making a super cheap disposable one.