Has anyone considered using plastic lumber for the road side flooring?
The spec sheet looks like it would be a good alternative material to use. It is more costly, and local availability would be a concern. Just thinking out of the box here. I am sure there are other sources for this product, but here is an info page:
Also see the specifications comparison link.
http://epsplasticlumber.com/plasticplywoodsheets.shtml