This is a tough requirement, as we've discussed before.

I gave up looking for the perfectly sized waterproof rigid PSK container. I decided to put the gear in a Seattle Sports Dry Doc pouch then put that pouch inside a lightweight nylon zip pouch.

The Dry Doc pouch is very robust and is made from a clear material that is much thicker and more flexible than typical vinyl. The zipper is extremely robust, far more than any freezer bag or poly bag. Still, I know that with time it will develop pinholes if unprotected. So that's why I put it in a sil-nylon zip pouch.

This gives me a reasonably light, very well protected setup. The sil-nylon pouch has 2 sewn paracord loops to connect a dummy cord. And I realized it had another benefit: items that are not dependent on being waterproof can ride in the nylon pouch but outside the Dry Doc pouch, freeing up waterproof real estate.