Can you heat a Class B motorHome the sam way as a car.

When I saw your question, I thought you were referring to the heat from the cooling water used by the engine to remove excess heat, just as in a car. Obviously, those heaters only work when the engine is running.

Have you considered a propane catalytic heater? They produce quite a bit of moisture, but are efficient and reasonably safe.

Propane furnaces are not as efficient and take electrical power for the fan.