As Sidecar mentions, they are not built for efficiency, but neither is most RVs.
Your in Alaska, I hope you are not planning to live in a RV for the winter..
You have at the most R3 in the floor and the walls R6 and roof R11 in the center, single pane windows with nice cold aluminum frames..
You have not much more than a oversized wooden fishing hut on wheels.
You are going to use twice as much energy whether it is propane or electric than what you think you might.
Yeah, you ARE going to be cold and broke..
I would be looking at super insulating before trying to calculate the cheapest heat.