Curious, I looked up the cot to see how it's made.

Could you cris-cross 1/8 inch bungee underneath, using the cot legs as anchors, and hold your clothing beneath you for insulation? A parka, a shirt or two and pants might give enough coverage. The bungee would perhaps also hold a purpose-built underquilt but what's the fun of carrying yet another piece of stuff?

Back when Eddie Bauer was but one outfitting shop in Seattle they carried a goose down cot that had tubes of down sewn into the underside. As a kid I thought is was the dumbest thing I'd ever seen but now, it sounds like a little slice of camping heaven.