What about a sit pad? I didn't carry one on my first thruhike, but I carried a torso length one on my PCT hike- you are often taking breaks or siestas on prickly ground - if you are a thermarest-er like me you sure don't want to break that out. One of favorite pieces of gear now is the Thinlight pad from Gossamer Gear. It's only 1/8 inch thick- I use it for addl thermal insulation under my Neoair, its 5ft by 20 inches. Folded in half a great torso pad, folded in fourths a very cushy sitpad. And it only weighs 2 oz! http://gossamergear.com/sleeping/1-8.html
Gossamer Gear Thinlight Insulation Pad 1/8"
Gossamer Gear Thinlight Insulation Pad 1/8"