You should be OK. What you have to fear is freezing oven night and remaining below freezing during the day and freezing again the second night. Now if it is in the 30s during the day and going down that night I might get concerned.
The trailer is a large thermal mass and it takes some time to drop the temperature in it.
I have frequently had nights in the 20s and awaken with the supply hose frozen but the trailer systems OK.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles