Extended season use of TT near freezing temperatures

we boondocked for the last two weeks in eastern oregon. Every night was below freezing, the coldest was 24F. Turned the thermostat on the furnace down to 45F (the lowest it would go) for the night. No issues. Overnight low temps in the fall are seldom long enough to cause freezing problems. Another issue when it seldom goes above freezing during the day.

our trailer does have an enclosed underbelly, but no direct heat vent to the underbody, just radiant heat from the furnace ducting.