I worry a lot abut that with my barbecue grill with the LP tank right below the burners with the open flame.
The heater does not operate unless there is water flow and there is also an on - off switch and then the on - off valve on the LP tank as well.
Since the heater automatically lights
reliably and the only LP fueled device on my camper is the water heater it is not too much of a burden to turn on and off the LP gas when I Park. I can't say for sure since I am just building the trailer, but I bet it will be OK.
I haven't looked, but are those ovens DOT approved too? How about the small catalytic heaters?
This might be an issue for someone with a LP refrigerator
that wants to keep the burners on while underway, but there is no LP within my trailer. All electric except for that water heater. These don't use much gas and I was tempted to use throw away 1 lb. bottles instead of the 20 lb tank.
The plumbing is all PEX 1/2" by the way with Sharkbite fittings and crimps.
Also these heaters are the primary way most of the rest of the world heats water. This is why they are so inexpensive and available.
As to installing inside the problem is not so much the vent (which is a problem unless powered low temp), but rather tin incoming combustion air. There are larger units that have a coaxial vent that feeds combustion air from outside and exhausts the fuels as well. These are more expensive and I think a little overkill.
I think the way I did it is a good compromise with no combustion inside and no LP gas lines either.