Has anyone had any experience building a 5' X 10' foam core platform to mount the track?

This is similar construction to the common household door but increasing the thickness of the materials. I am thinking 1.5" foam with 1/4" plywood panels top and bottom.

It should have the effect of a platform that would be more rigid than 3/4" plywood but only 4 pounds heavier that a piece of 1/2" plywood.