So why not do what we did back when I used to fly and ground the thing?
When we were fueling up the Cessna's the first step was to clip the ground
wire to the aircraft and then enjoy the pleasure of fueling.
For this instance have a three way clip - one connection to the gas can,
another to the vehicle, and the third to the fuel pump's nozzle.
That being said I do remove the gas cans from whichever transporting
vehicle and put them on the ground. Since the various transporting vehicles
are things like sedans with big trunks, a Ford E150 van, and a Chrysler
mini-van I don't want a build-up of fumes inside the vehicle but rather
outside it right next to the gas pump where it's nice and safe ;-)
I seem to recall seeing a TV show where they did some (NON-MYTHBUSTERS)
types of experiments with this type of thing and could repeatably cause a
spark between the pump nozzle and the vehicle. They actually got a fire
going a couple of times. Very scarily impressive.
My parents once owned a Citroen Mehari. Plastic body. Cycolac ABS
plastic body. Never had a problem with it but of course the gas tank nozzle
on it was steel.
Just my rambling $0.02 worth.
Suggested annual donation $12.96