Hard to make generalizations without know more about your RV and how it's equipped. With electric tank heaters and valve heaters there should be no need to winterize but without those features you COULD end up being unable to dump holding tanks under some circumstances. Chances are your plumbing located above the floor or inside an enclosed belly, would be safe from freezing with some electric heat inside the trailer. Each case is different so use some common sense and think the problem through. It might be 50 degrees at one spot inside the trailer but if it's 28 where the water is, it'll freeze.
Good luck / Skip