Not all camp grills operate at 11" w.c. at the orifice. If they did, you would just need a needle valve at the grill to turn down the heat, if needed, when connected to the 11" rv quick connect. I had a camp grill that ran at 15" so when I connected it to the rv connector, 11" only gave it really low heat and it wouldn't cook anything. The grill mfgr tech support might be able to tell you the orifice pressure, if you get lucky, so you can then figure out what you need for the hose connection and control. BTW, I'm gas certified and I make all my own stuff.
It's too bad Marshall doesn't make this reg any more. Craig