[TexasCamper]

Before I try to start the hot water heater, I light up one of the oven's range burners. That usually takes a minute or two as the propane line displaces any air in the line.

This step has eliminated previous problems I had with getting the hot water heater to light off. So I'm wondering if a light-off problem was allowing some propane to leak by.....even then, I would think the propane leak would be on the outside and not the living area of the camper.

I've camped on some windy nights (one night my young daughter thought the wind would blow the camper away!), and haven't had the issue you've described. But I think wind is plausible.