So i was thinking about hammock insulation and integrating a hammock and a store bought sleeping bag together to eliminate the need to buy a hammock, an underquilt and an overquilt for use in cold weather.

what if you built a very narrow hammock, lets say 30" wide and took a sleeping bag and cut holes in "neck" and "heel" of the mummy part. now thread the hammock through the holes in the bag, hop in and sip it up. obviously you'd have to sleep on your back but i keep having this gut feling there is something else i'm missing as to why this wont work?

I know someone will be able to point out the flaw(s) in this design other than it being pretty unstable becasue of how narrow it is.