I don't know what your ability level is, but they are very easy to make. You can buy yourself a nice piece of foam at UFO or any upholstery supply and build it very easily.
We made one out of 3/4 in plywood. We had it cut into 3 pieces so it would be easier for us to take in and out of the van. I covered it with foam and then with some denim fabric. We only take it along when we camp with the grandkids.
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Dick and Anne
DABEE a 2006 Ford EB250 with penthouse top.
Life Is Good.