be careful not to constrict the loft of the bag... i found a wool blanket was warmer under me before teh cold air pads.... and its loft is hard to squish out....

another idea is putting a heat sheat under you... it oddly works well ... maybe you can scrounge one or two... i also found you can use em as a fire reclector if you put em a couple feet away from the fire...

personaly i would build wind breaks and then build the tarp into the windbreaks. dig down and put my dome tent inside with the ground cloth etc. then use every one elses idea... as well.

its not easy campin that cold...... i would let ya use my portable electric blanket and jump battery if you were closer lol.