a drivable MH with a frame mounted tank is NOT exactly a TT with bottles on the tongue , and AMERiGAS bottle sales refill
is doing a CYA .. lawyer speak, they tell what not to do, "everything"
so nobody can claim they were told it was oK to do something common sense said no to
I suppose you would like refrigerated BIG rigs and railroad cars to turn off their lp fired generators and cooling system while moving so that your frozen food and fresh meats spoiled on the way to the grocery
IF the LP systems were not safe the DOT would not allow them on the highways
the on board generator to power your fridge is the best bet, you don't have to buy anything but a little bit more gasoline fuel
i had LP fridge in 3 prior RVs and in this one when i got it, and i always drove using the propane, unless the tank / bottle was empty
electric was simply a backup measure, something to fall back on
i know only two people that run a RV fridge from electric , and you already heard from one of them, and he told you to beef up your system,