OP, "Do I think it was worth it?" If you are paying for the power.. heck YES. Heat pumps are 2-3 times more efficient than heat strips, even at 35 degrees they are 1.5 to 2 times more efficient. Even if you had a 90+% efficient gas furnace in your RV, instead of the 75-% you are not paying $1.40 (current home propane price) when you get propane is small amounts. Anyone paying less than $2 for propane for your RV?
Once it gets below freezing it's time to start heating your water systems so the cost/efficiency of heating makes no difference.