How about using a propane heater used for camping in your bus?
I don't know if this has been suggested before, but it sounds reasonable.
It would be safer than a gas heater, cheaper, and probably as cost
efficient.  Just called local camping surplus store, he said this
would be great for vans.  From $24.95 and up, some come with
safety mechanism where it shuts off if tipped over.
Could this be the solution to our problem?
I know about an odor or that it might ruin headliner, but my bus
smells anyway plus the headliner is faded yellow in some parts.
Sound good?!?!

Paul 
79 bus