I didn't like the ideas of 1) using a long hose from the RV propane system carrying the HP side pressure or 2) lugging around a full 20-pound tank. My compromise was to get a "squatty" 10-pound tank. It has the same base ring size as a 20-pounder, but weighs half as much.
I bought a base stabilising ring from CW, bolted it to a square of 3/4" plywood, then bolted the plywood down to a cargo-bay floor. I put it close to the front wall of the bay and added a couple of bungee hooks to the wall so I could restrain the top of the tank. They turned out not to be necessary. The tank fit very snugly in the base ring, and if it did come partly loose, it would hit the wall.
Works just fine.
Keeping the cylinder half full makes it lighter to move around.