.... I'm still trying to figure out hammocks when it's cold with out breaking the bank..... (rare here in the east).
I'm suprised I've not seen anyone sew 3-4" down or Primaloft tubes all around the cot for insulation, like a big down cocoon. Or maybe just a sleeve for a down air mattress, then you would have and insulated base and use it on the ground too.
I've got a down air mattress in my Stephens Warmlite bag. It's heavy, and a bit bulky, but man does it sleep nice. Almost better than my bed.
DG