There is another way to go if your looking for a little versatility in camp.
I have a Thermarest. Don't recall the exact model, but I believe it's a NEO style with the contour shape and inner core with the perforated foam for weight savings.
Inflated it's about 1 1/2" thick or so.
I don't bring a chair and usually find a natural backrest and sit on a piece of a old Thermarest closed cell foam pad to ward off the cold/wet ground.
I ended up buying a 4' version of this pad. I don't roll it and attach to pack, I stand it on edge in my Granite Gear food pack and put my food containers inside of it. Quiets the pack/insulates and if I go over I know it will float.

At night I lay that under the top portion of my NEO and get another layer of padding.
Serves multiple purposes and I don't think the combine weight would what your looking at?