Yes I do, luckily the laws of chemistry and physics works for truck campers.
Gasoline vapor is 3-4 times heavier than air, so it quickly sinks in calm air. In gusty situations gasoline vapors are quickly diluted by air to below its lower flammability limit.
While gasoline's flash point (temp above which the vapor will ignite when a spark is provided) is -43C, the gasoline vapor flammability range is limited to 1.4-7.6% by volume in air.
It used to be NFPA codes prevented gas hot water heaters and gas clothes dryers in a garage, as there was a concern that a pilot light might ignite gasoline vapors near the garage floor. The solution in the code was to require these appliances to be installed at least 18" above the floor in the garage. New designs make this unnecessary.
My TC hot water heater, furnace and refrigerator flame sources are all 4-5 feet off the ground. Very unlikely to ignite gasoline vapors on the ground from other cars at the gas station or minor spills. Much less if there is a breeze (can't discount a smoker that throws a lighted cigarette on the ground).
Some may worry about the vapors from their own vehicle. Hypothetically, filling a 30 gallon tank of gasoline would displace four cubic feet of gasoline saturated vapor. If it took 3 minutes to fill the tank and there was only a 1 mph breeze (1.47 feet/sec) that vapor trail would be over 522 feet long and mixing while it goes. Once that vapor is mixed 12 fold with air it is within the flammable range, yet being mixed another 6 fold with air and it is below the flammability limit. Thus the very low number of gas station fires.
Propane has a flash point of -104C and vapor flammability limits of 2.1 to 10.1% by volume in air. Its vapor density is 1.88, also heavier than air, so it too sinks in still air and is readily mixed with air to below its flammability limits at normal driving speeds. Thus no issues reported for driving with propane on, even if the flame goes out.
For those with gasoline powered trucks worried about possible risks vs. probable risks, you can:
1) continue to shutoff the propane while fueling and driving or
2) lookup up the actual data on gas station fire incident rates and NTSB data for vehicles and determine the real risk level and decide to not worry.
3) switch to a diesel powered truck. Diesel fuel flash point is >54C (>130F) and will not ignite below that temperature, even withing the flammability limits of 0.6-7.5% by volume in air.
Another way of putting risk in perspective is according to social security data the probability of living to 100 are in the 1 in 1,000 range depending on the birth cohort year. Once at 100 you have a 50/50 chance of living 1-2 more years. If you are alive after 1-2 more years , it is another coin flip to live another 1-2 years. It takes a lot of heads in a row to make it to 120 years. Not impossible, just very improbable (1 in (1,000 x (2)^15)
Log Scale Version
25% of my cohort died before my 40th high school reunion
50% of my cohort won't make it to age 70. They lost the coin flip by waiting to retire at 70.
Cognitive bias makes us worry about high impact / low probability risks by focusing on just some of the data verses all of it. Worry reduces your life expectancy.
Since time is at a premium, worry about and take action on the high impact / high probability risks and high impact / medium probability risks. Ignore the others as they are just distractions. It is about making decision on where to spend your time based on your best judgments of all the data, not your worst fears.
Retire early and enjoy adventuring in your TC
