I got a Pacific Outdoor Equipment Insul-mat Max Thermo last winter. I've only used it on the floor, but it was very comfy overnight when somewhat underinflated (fully inflated it's too hard). It only weighs 22 ounces, as I recall, and it is comparable in thickness to an air mattress. I bought someone's 3/4 length version a couple of days ago; haven't gotten it in the mail, but that one is only 15 ounces.