Plumber wants to bring a top hat heater out and another guy says "I have a couple torpedo heaters you can use" Im thinking a regular old house furnace with an exhaust would be much better. Our propane provider says they have one we can borrow. Think thats a better option?
Furnace is good.
What are your walls at present?
I had my vapor barrier installed to help keep the heat in as well. I don't recall any mold on that. There was condensation though.