Do you really want a long hose carrying high-pressure propane running across from your rig to the picnic table?
On the other hand, I've heard of people taking the built-in regulator off the Weber and running it off the low side of the RV system and not being able to get the grill below about 600 degrees, because the RV's regulator is too high a flow rate to be able to "trickle' at the rate the grill burns.
I chickened out when we got a Weber for the RV. I didn't want to be humping a 20-pound tank around, so I bought a low-profile 10-pound LP tank that has the same base ring as the 20-pounders. I also got a CW base stbilizer ring, which I bolted to a stowbin floor. The "squatty" tank is so well restrained for travel, that I don't use the bungee-cord restrant I installed.
I keep the tank about half full, so it's not too difficult to lift in and out of the stow-bin. It works for me, and is about as safe and efficient as I can get. The grill works fine on that tank, too.
Frank and Eileen
No longer RVers or FR owners