The sleeve design of the Trekker fits over an entire Therm-a-Rest inflatable sleeping pad or equivalent, and is available in either 20in or 25in widths. It will add 18oz to your load but if you anticipate any significant down time this accessory is guaranteed to make being tent or campsite bound much more comfy-cushy.
There's an integrated pillow pocket, the straps adjust easily without having to move your moneymaker, and they unclip when it's time to get horizontal. You can double over the pad for added seat cushioning, or leave it extended for true lounging goodness. When it's time to fly just remove the four plastic seat stays, tuck them into a pocket at the foot, roll the whole thing up and buckle it. Just call it a pound of prevention.