Thanks Steve for the info. I'm going to look into the matress pad, I like how it intermittently shuts itself off and then on as needed.
For now I have flannel sheets and my sleeping bag which is rated to zero (if you believe that) and I will wear sweats. I can also run a short extension cord from the trailer (AC power) to a small ceramic heater to knock the edge off.
Why hasn't anyone found a dead bigfoot? When was the last time you found a dead deer, bear, coyote, fox, squirrel, etc. that died in the woods.........Hmmm.