My experience was only with a pop up trailer and everything else was hard side, but these things don’t change:
1. The less insulation you have, the more fuel and battery you will burn to keep a desired temperature.
2. The greater the inside air temperature difference is verses the inner walls, the more condensation will form.
3. Air exchange and movement is vital to keep condensation down.
4. Once your heater gets to the point where it is constantly running and not cycling you have reached your limit. You can add insulation to reduce heat loss but now know the minimum temperature in which you can comfortably camp.
I camped in hard shell campers down to single digit nights, but only down to low 30’s with my pop up because I couldn’t keep it comfortable when any colder. I expect a pop up truck camper will be able to hold heat better than my trailer but don’t expect performance like your previous Northstar hardside.
