We have a 2017 Lance 1995. It is 4-season. That said, I have had water lines freeze into the bathroom in 7°F, and the line to the water pump froze at -2°F. I stayed plenty-warm in the trailer (furnace ran just under half the time with thermostat set at 65°) when temps were below 10°F.
I don't know if any TT is really going to fare well with temps below 10°F longer than overnight. Even with furnace running, the Lance has water lines running around the perimeter, so they don't get heat, even with the cupboards left open. Around the perimeter of the bathroom gets no heat from the furnace, that I can tell.
Good luck!