I spotted an old Woods down-polyfil blend bag in the local second hand shop yesterday. That sucker is flatter than a pancake. (It's more like a crepe.) At first glance, it looked more like a tarp than a sleeping bag. The outer shell is in fantastic shape, and looks like it provides a good vapour barrier for the fill. For $10, I'll try to restore the loft and, if that fails, it should make a good ground sheet. Either way, it's too heavy for anything other than car or backyard camping so it's destined for a home in the back of my Jeep.