While it is a subject of contention, if we did a poll, I'll bet that at least 80% of the folks here use propane when they aren't connected to shore power, including while driving. With the protection devices built into propane tanks themselves in addition to those in the refrigerator itself, it's very safe to do so.
And the likelihood of it even being an issue at a gas station is close to nil. For anything to happen, the minimal gasoline vapor escaping from your vehicle while you're filling up would need to a good 10-15 feet horizontally and up somewhat (keeping in mind that gas vapors are heavier than air), in an open environment, to the vent of your refrigerator, ignite, and then race all that distance back to your fuel nozzle and ignite it as well. Virtually 100% of gas station fires are caused by static electricity or some other source igniting the vapors within inches of the fuel.
It's not absolutely 100% safe (nothing is), but you're literally about 10,000 times more likely to get involved in an auto accident while towing your Pod than you are to encounter a problem with running your propane while driving or even filling up.
If you're really concerned about it, just turn the refrigerator off before filling up, remembering to turn it back on when you leave.
If you want to run your refrigerator on 12 volt, you'll almost certainly need to have the power line running to your Pod from your tow vehicle upgraded as the lines are seldom of sufficient gauge to power the refrigerator. Otherwise, you'll wind up with a dead battery, which causes long-term harm to the battery itself.
Regarding law enforcement, I have not even heard a rumor of an office asking whether they were running their refrigerator on propane while driving.
The only time I've ever heard of a problem with this is below. It appears that the guy somehow sprayed the outside of his RV where the refrigerator vent is, and the gasoline ignited. Even the local fire inspector wasn't sure that the refrigerator running on propane was the cause of the fire. With hundreds of thousands of RVs on the road, and a large number of them doing this all of the time, I think we can safely say that running your refrigerator on propane while driving is safe.
http://www.houmatoday.com/article/20100325/ARTICLES/100329598