Thought space heaters still needed 240v to run the fan? Bit pointless if it does.
Never seen one of those.Every one I have looked at all need an electric feed for the fan.Would not fancy running that with all the doors closed in the morning, will make the van stink.Just my opinion though.
LPG?It'll produce just as much condensation in the back of the vehicle as fuel it burns. If you used 5 litres of fuel it'll deposit 5 litres of water in your van every night too.