My mother has been using Oil Filled space heaters for years and years. She has 3 of them in her house. Leaves them on 24x7. In 20 (plus) years, she's had only 1 fail. It died, would not heat any more.
They should work fine in an RV as well.
Suggestion: If you are going to run a separate electric heat source in your camper, run a separate electric cord to the campground pedestal and plug it into the 15-20 amp household style receptical. This way, it won't draw amps through your camper, using up precious 30 amp or 50 amp power.
If you decide to run 2, run two separate extension cords outside the camper and plug in to the shore power pedestal. 1500 is a LOT to draw and you run the risk of popping breakers. Popping won't hurt anythng. It's designed to so. But it's frustrating not being able to keep and maintain the electric usage you want. (and the aggrivation of fumpling around in the dark to re-set breakers.)