Wallyworld has, at least in my neck of the woods, a 90" long by 40" wide sleeping bag called the SleepCell. Center zipper design, rated down to 30 degrees according to the package, It has zippers down the side to help it vent in warmer weather. I wouldn't risk it below 40 degrees. I picked on up to adapt as an underquilt for my ENO Singlenest. If I cann't make it work then at least I know, from this last weekend's Boy Scout outting that I can stuff my regular size 30 degree mummy bag into in and increase the rating for cold weather camps with the Troop. Looks like I may stay a ground hugger for a while longer when it comes to cold weather camping.