mktrat wrote:Two words: Horse Mat.
Tractor supply (or similar) is your friend here. Nice and thick, a bit of cushioning, decent weight so it wont move. Just trim to fit, and your good to go.
I would suggest some all plastic type velcro stuff epoxied in a few locations to help it stay in place, but if you take your time trimming it you probably wont even need the velcro.
Also in the same realm, Semi Truck mud flap, which you can find in the same places and trim. There thick, ribbed, decent weight, etc
I was suggested such when looking for mats for my old house dirt crawl space. Other mats were disintegration during flooding and such; these things are made to handle that.