"I think it's a lot to do about nothing. I going out on a limb and saying the stats on this are all most nil. I use the propane to cool the fridge even plugged in (why turn it off it uses so little propane it's not worth it) if the flame goes out the gas shuts off."]
I imagine that the stats on this are, as you say, almost nil. But why take a chance? It's impossible to prove a negative.
Now, even if it is true that once the flame shuts off in the refrigerator's burner, the line from the tank to the refrigerator's gas valve is still pressurized. Hence, there is still the possibility that gas can escape from the tank should any portion of the line from the tank to the refrigerator's gas valve somehow be compromised.
["Traveling down the road the camper is a great big low pressure area anything in side is going to leave. If someone is going to clip the rubber lines they probably will take the tank out too open valve or not. Propane gas dissipates pretty quickly the biggest danger is the liquid."]
Not necessarily. Let's modify our original scenario and say that the rubber line from tank to trailer body is in some way compromised: dry-rotted, nicked through to the inner core, whatever. Then, let's further say that propane is slowly leaking out through the breach in the line. Now, let's further further say that we're not traveling down the road, but stuck in a lengthy back-up. There now is no low-pressure condition whatsoever, but rather propane pooling up underneath and around the TV. Moreover: Propane gas does not "dissipate pretty quickly," unless it is discharged into truly open atmosphere. Rather, as I stated previously, it 'likes' to pool in pockets in corners--or any low space it can find, because, again as noted previously, it is heavier than air. Again, the situation that would cause the most concern would be one in which any hypothetical gas leak is inside the trailer itself, the one place in which an explosive gas-air mixture could develop.
["The only restrictions I know of for camper propane is tunnels."] )
