(1) you need to know that there are at least 2 incompatible propane quick-connect systems that have been used on RVs. They LOOK identical, but are just enough different (no doubt by thousandths of an inch) that they will not work, one with another.
(2) I don't buy the "wrong regulator" business. It's nonsense as far as I can tell.
(3) I use the propane quick connect on my TT with my portable grill. I had to buy both of the two disconnect plugs to find the right one and return the one that didn't work to get it right, but my grill works perfectly. It IS true that there are single stage as well as two-stage regulators, but as far as those being incompatible, nope. they all seem to regulate the pressure to the same level, it's just in how it is done.