Ditto what Law Dawg said. I tried a partially deflated REI Camp Rest pad in a double layer BB. This is a plenty long and wide pad, so it should have fit pretty well with no shifting around. But, it still moved around, wasn't comfy, and drove me nuts. The UQ just plain works. That's not to say that an UQ doesn't take a little bit of tweaking, but it's minimal, and once you have it dialed in, you're good to go.