There are a lot of choices when choosing a method to heat your van. This article from the Consumer Product Safety Commission is informative. It appears that wood and coal heating results in the fewest annual deaths from carbon monoxide (CO) poisoning, and that propane/natural gas results in the most. Of course far more people depend on gas heating than wood or coal, but it does tell a story, and I think the story is that people using wood/coal/solid fuel heat have to give more of their attention to the heater or stove, and that solid fuel heaters are much simpler devices with less to go wrong. Propane devices on the other hand, are mostly set and forget, and if something goes wrong it might be harder to detect. Whatever you use however, you should maintain a CO detector in your van.
We do not have any, but both propane and I believe co are heavier than O2 So most likely it will run out the bottom somewhere anyway. Good ventilation is key.
The mr buddy heater we use has a low o2 shut off.
Propane is heavier than air, and will eventually vent through the bottom (if there is one), but CO is a little bit lighter than air. Because of diffusion and Daltan’s Law of non reacting gases, CO mixes with the air, so it will not run out of a bottom opening in your van. Since diffusion is a stronger force than the differing molecular weights of air vs. CO, it stays mixed in your van, blocks the oxygen receptors in your red blood cells, and results in death.
It doesn’t matter how much oxygen is in the air; if there’s too much CO you’re in trouble.
I definitely vote for detectors whether you think you need them or not.