There's 2 things that I don't like about the portable electric heaters.
1
It's close quarters in an RV to begin with, so there is never a good place for a portable electric to begin with.
2
The thermostat is on/in the heater so it senses the temperature of the unit before the room/rv.
In our last 2 mh I have installed a Toe Kick heater under the kitchen sink/cupboard. They use a thermostat just like a furnace.
I wire it to the same breaker as the air conditioner, leaving the AC hooked to the t-stat with the LP furnace. Now the electric heat/furnace and AC can't both run at the same time. If they try to the breaker will trip.