My New Marine Cooler - Need Your Input

I thought taking one of these Costco bags and turning it inside out and then spraying it with something like Flexseal. Should keep it lightweight and flexible, but a bit more spine resistant. If it develops a leak, just add another coat.

It'll be an issue with pretty near all soft-sided coolers, Eugene.  Check Wally World again - they have a massive number of plastic containers in almost every size and shape.