I have a group 27 battery in my 16’ TT, I almost entirely dry camp, and I can get the best part of a week out of it. I agree with other posters, the furnace is your problem and the best solution is probably to have two batteries to switch off and minimize the furnace use.
I used my PU on winter hunting trips in sub zero weather and didn’t use the furnace. I found that when I got up and lit the stove for coffee the PU was comfortably warm in a very short time. Of course I was tramping around outside in that weather, too, so I probably acclimated somewhat to it.
I’ve been in the 30’s in my TT and haven’t lit the furnace. Once the DW complained it was cold and I went outside and put my finger on the thermometer and turned it so she could see it through the window. It was in the mid 40’s so it wasn’t as cold as she thought it was.:D You can also dress a little warmer if it’s cold, there’s no relief if it’s hot except ac.
