While perusing through a local thrift store, I came across a military issue foam pad, complete with tie straps and mil-spec numbers stamped on it. It looks new. For $2 I couldn't resist so I bought it to keep in the car, with my car hammock kit.
Trying it out...oh my goodness...my driveway is softer! This thing would make better kayak rack foam. I have to wonder who tests this stuff for our service personnel? You'd think we would want them to be as comfortable as possible. My Ridgerest is a down mattress compared to this thing. It must be some subversive plot to keep our brave guys and gals tired.
Come to the 20th century, US procurement office! (maybe these pads are designed to be bullet proof....haven't shot it. yet.)