Is it safe to use heat tape on inside water lines?

We left the heat set at 70, have 2 ceramic heaters and 1 oil heater going, our LP furnace hardly ever come on. Our TT has the All weather package, but no heated tanks like the Polar ones do.
Like I've said before, not doing the winter camping a lot except Thanksgivings in OK and Christmas in IA. Just like the challenger of not freezing while we are their.