I have a sedan, so mine is a little different. I pulled all the felt out and made a plywood floor that was painted with bedliner. I also added tie-downs so stuff doesn't get mangled when I corner hard.
I haven't tried, though it may work... What if you took the felt stuff out and sprayed on a few coats of either bedliner paint or the flexible bumper paint? If I had a wagon, that's what I would try.