If you are going for the Thermarest rather than the big thick air mats, I use a 3/4 mat with a section of old closed cell foam mat to go under your lower legs when sleeping. Then you also have a sit mat and you can use it as a packing aid for the barbag too.
And befoe I got distracted by fire I was going to say that this ^ is sound stuff. I’ve done overnighters with a roll of foam mat, packed by wrapping around the sleeping bag then using ferns etc to pad out the ground. Warm and comfy and half the fun of all this is doing it on the cheap.
For a bar roll, a bit of foam and some 1″ webbing strap and buckles works well enough.