I'll have more stuff to post up in a bit, but this is the
2" memory foam pad that I got off amazon. It DOES fit with the factory pad (folds up just fine). I was really really trying to find one that came with a cover, but I could only find one in a king size, so I skipped that for now.
My wife who complains about most beds, slept better in our tent than our real bed at home lol. This was with the pad linked above and the factory pad under it.
California king is what I went with, it is almost as wide as the factory pad, but it is slightly shorter. I went for this over the regular king size since the king pad would be both shorter in width and length.
I would highly recommend the cal king size (at least for the pad I bought) as it is nearly perfect.