The good air quick couplers like the commercial ones from the coupling supply stores do not leak.
I have 3 sizes of them, and a 1/2 inch one permanently mounted to my accessory tank so that i can run my 1 in air gun as well as all other air tools.
I would not hesitate to install a quick coupler for a propane line inside my barbecue bay so that i could just drag the Colman travelmate out and attatch the hose. (which would go in line before the regulator as suggested in earlier post)
Now that this question has been posted, i think I will do this, as it will be perfectly safe.
It won't meet code of course, but I wont tell the RVIA plate...