Have you found your mattress solution? Since the post is "fairly" recent I thought I would add my 0.02. I recently bought 5" queen and king LUCID brand memory foam mattresses for our HW from Amazon. They are SO MUCH better than the prior 4" mattresses. I just used an electric fishing knife to cut the memory foam down about 3" on one side to make it fit our bunk ends. It was one of the best things I've done for our camper!