This past week at my VA hunt camp, when the temps got down in the teens and twenties, my 1200 parabolic heater at high would only work (or register) 960 watts using my Champion 1800 generator. Maybe it was because I was using two cords which were too long and maybe too smaller in diameter.
Anyway, I was not too happy with the inside temps. I did not run it while sleeping and my ceiling insulation was not in yet.
I will guess that when I finish my CT with all the proper insulation and wiring that my results will improve drastically. If I use electric heat, I will consider a smaller profile heater, 1000W or greater, and if it use a generator, I want to go after the 2000W Honda unit.