How about coating the bottom portion of the bag with a product called Plasti-dip? The product is designed to coat the bare handles of tools with a plastic coating. I have used it to coat jig heads and the stuff is bullet proof. I would paint it on the inside of the bag, up an inch or 2 on the sides.

Here is a link to the product...

http://www.eastwood.com/paints/plast...FUhgMgodY1IARQ

Brad