Have you guys ever seen a portable blow up bed from places like Cebalas and other outdoor camping stores? The reason I say this is they have bed frames that fold up like an accordion and pack up into a travel bag. Super light weight aluminum and supports 500 lbs. I used one for a riser for a long time, I just put sections of plywood on top of it and gaff taped them together so they wouldn't separate. Worked perfectly and the frame folded up into a bag I could hold in my hands. It weighs about 15 lbs. Here's a picture to show you what I mean. I never had any trouble with it at all, my platform area was 6' x 8' and I think the area for the mattress was 4' x 6'. It's 18" high. It cost $100 plus plywood sheets.....smooth as a gravy sandwhich!