Hi,
I believe you need to rethink your attempt to live off the grid.
Have a look at this thread:
winter campingI've RV'ed at -39 C (-38 F).
Propane in small tanks won't support a rate of flow that will allow you to run the furnace in extreme cold. You will need at least two 100 gallon tanks and probably a tank heater would be a wise addition.
The wave heater someone suggested is an invitation to extremely high humidity levels. Those levels may form ice inside the walls of the RV.
If the kerosene heater is not vented, the same issue exists.
If you wish to use a safe heater look at the Platinum Cat, which does have a chimney.
How will you handle water and wastes?
