At this time I am not interested in living in a van but for a long time I have wanted some kind of auxiliary heater for my minivan. It could be powered by diesel or a five gallon propane tank. I think it strange something like this is not off the shelf as unfortunately a lot of people live in their cars or vans because they have no where else to go. For winter living it would have to be better for the engine and for fuel consumption.
An under-rear-seat, gas-powered (got its fuel from the tank) heaters used to be an option on VW vans. Aftermarket offers Propex, but they ain't cheap. Plan on a couple of thousand if someone else does all the work. $700 for just the heater, IIRC.
Depending on your expectations and how you travel, the easiest option might be a $15 electric space heater and an extension cord. Won't work when boondocking. Useful at campsites with electric.
Made-in-China diesel heaters are <$200 on eBay and there are reasonable reviews on Youtube.
