What do the readers think of one of these? $400 for the very few times it would be used - perhaps a sealable hole through the floor of the van where the duct could run to. The unit under the van out of the weather, gas supply from an existing gas bayonet. A few downsides to it - would have to get in & out of the van to turn it on/off etc.. battery recharged via a small invertor. DOS
https://www.snowys.com.au/ducted-camping-heater
https://www.snowys.com.au/ducted-camping-heater