In article ivTQa.69985$H17.20537@sccrnsc02,
Jay Honeck wrote:
Our back seats pop out in seconds. We've got two pieces of 3/4 inch plywood
that lay in their place, stretching all the way from just behind the front
seats into the luggage compartment. Turns the plane into a pickup truck!

You should check out some tempered hardboard at the local lumber yard.
It's extremely rigid and durable even in 1/4" and much lighter than
3/4" ply. You can get it with a white laminate on one side, too.

--
Ben Jackson

http://www.ben.com/