I had a couple friends who took their motor home on a weekend vacation; a dump truck ran a stop light hit the motor home right where the propane tank was mounted midway of the vehicle. The fire-rescue team said they may have survived if the gas valve at the tank was shut off. The line broke to the tank and the RV exploded. The dump truck driver survived because he was able to exit his vehicle.
That paint stick that was made to prevent the gas stove knobs form being pushed in is also a great idea.
I always shut the propane off when traveling that way I don't forget when fueling up. Arriving safely to my destination is my top priority! JMHO