RE: Propane on while driving
Roger, I've heard those argument also and they don't make sense.  All modern
propane fired device, even our much maligned Dometics in our Westfalias,
have a shut off if the main flame goes out.  Same for self igniting gas
devices like stoves and refrigerators used in the home or in RVs.  So the
flame blowing out while driving shuts off the flow of gas.  That's why you
have to hold the button for a few seconds after lighting the Dometic, to
allow the thermocouple to heat to the point that the propane flow is held
open.

As for the ferries, that concern I completely agree with.  All it would take
is one gasoline leak from one other vehicle for fumes to reach a pilot light
on a propane device, like our refrigerators, and the mixture to be just
right to get an explosion and fire.  How many people have toasted
themselves, or at least their garages/houses using an open container of gas
to clean auto parts in the garage where the gas fired hot water heater was
located?