I have found that the operational maximum for an inflatable mattress is 250 lbs. Which explains why my 255 lbs of me ends up on the flat ground every time I use one, although if I examine the mattress with either the soapy water (lookin for bubbles) or in the pool (again lookin for bubbles) method I never find a leak.
So, I bought 13' of 45" wide pillow ticking, folded it in half, timmed off 10" lengthwise, and sewed up both long seams. I now have a long pillow-ticking bag 6' 6" x 35", that I fill with a half bale of straw and tie closed with a leather thong. It compresses down to about a 2" pad, insulates very well, is authentic, and when empty it rolls into a nice, neat bundle, so takes up very little room in the car or on my back if I hike into a site. (Course the site has to have straw avaiable).
You also end up with a 13' x 10" strip of ticking for patching round ball, etc.
LD