that little trailer was for me and my wife when we had no kids. it was the ultimate towing trailer for trip in winter. I build it myself and it was extremely well insulated. 700 watts of heat was plenty to kick us out of the trailer in a -20 degres C.
I now have a argosy 24. As i said, with 2 1500
ceramic heater, i can do winter camping and i have fun. It s never been a issue. On the recent trip, i pass a few days with my little 2 year old daughter and we used catalytic heater. We only keep the front bedroom heated during the night but we had a great time. I still prever ceramic heater as a heating source.
While the airstream isnt a marvel of insulation, with a few modification and the right gears, it does work pretty well for us. But once again, my wife and my honeymoon was 3 weeks on Mt-Everest during the winter so i guess i m a happy camper in the cold!
PS: i dont camp in the heat....i HATE IT!!! if i have to use the AC... it s not camping!!!! i head up the mountain instead! i could not survive the toaster test!