Don, as with any appliance in a gas system, you definitely need a manual shutoff somewhere in that line to the grill, particularly with that quick disconnect. I am not a fan of quick disconnect fittings, but they are ok as long as you use the proper fittings. Make sure they are rated for gas, and not just a shop air connector. We have all walked into a garage and heard a quick disconnect hissing off in a corner somewhere which is fine for shop air but scary for gas, and propane will attack and deteriorate some grades of rubber so you need to make sure it is rated for gas. I would suggest a connector designed for natural gas that you can get from your gas company or a good plumbing outlet, or one from Paulin
PAULIN OUTDOOR PRODUCTS - INDOOR HEATERS they specialize in propane accessories. Which reminds me, they make a really nice line of gas lights if you are really trying to stay away from power for dry camping, but that is another subject. Anyway, use a manual shutoff either at tee where you branch off, or at the end of the line at the QD, as long as it is where you can get to it. I just don't trust the QD's, particularly when you are driving, so just make sure to manually shut off the gas when not in use.