oil radiator heater

the heater will not keep pipes,etc. below the floor from freezing.
bumpy

Did you c o insider just blowing out the water lines?
The heater will work, depending on your location.

For the small cost of the RV antifreeze it seems cheaper than running and electric heater all winter.

Perhaps if you're only talking a few nights per season...maybe.

Yep turn off the caps. What city/area are you keeping RV for winter?

Please turn off caps lock. It is considered yelling here.
To answer your question, maybe! Where are your water lines, your water pump? Better to blow the lines out and add anti freeze to the "P"traps no matter what else you are considering.