Heating

That's what I use very safe & I feel comfortable leaving it on all night. The fan heaters have one dissadvantage and that is that the get the van hot & switch of & on all the time and are in the confines of a van noisy. Small column heater cost me about $45 with timer & thermostat...

Get the van warm with the air con and column heater then turn the air con off no noise and your snug provided you have no chronic door openers.
However we use a fan heater with a thermo and find it very good but noise does not worry us as we are solid sleepers with no tin lids.