op wrote:
The weather forecast is 65-70 during the day, but dropping to 30-32 at night.
One size don't fit all if temps drop to 30 degrees.
Depends on wind speeds.
Depends on how well the under side is insulated.
And depends on the under side open or enclosed.
Is the trailer a full four season unit or just a three season unit.
Lots of variables why some unit can have a frozen line and the unit next door doesn't.
We had a frozen line in 29-30 degree temps along with 18-25 mph winds in early December even with the heater going in western Oklahoma. I plugged a extension light in stuck it next to the pump and it thawed in 20 min.
I have a good indoor/outdoor temp guage. I drilled a small hole in the floor next to a wall and fished the sender under side. Its protected from road debris/sun and gives me the exact temp in my location.
Its your unit and you have heaters so use them.