[bluzer1]

Might have been even easier just to use dry direct-to-air electric heating elements?

Agreed but imagine the in-cabin fire hazard after a decade of dust accumulates!

 

[bluzer1]

That's not as scary as my dad's VW Vanagon which had a gasoline heater. Lighting gasoline with a flame for that booster heater could be disasterous if corrosion hits any of the parts

My dad had that option in the second of two Beatles.
They tell me I used to ride in the cubby hole at the back, no safety in those days!