I've got several of those fleece bags from Coleman (walmart...$9) for laying around the house and overnighters for the kids. Two things I don't like....they are cold if the room goes below 65 and they don't crunch down well for packing. The flip side is they are indestructible and handle endless washing. I've car camped inside two of em' which worked pretty well. They are NOT wind proof.

The poncho/shelter idea is good. Why not a bedsized sheet of coated ripstop or silnylon to shield you from the cooties? It would double as all sorts of things like rain gear and a tarp. I camp with a Robinson poncho, but a sheet of material would work fine.