We bought a Q-220 for the RV, only to find it was 3/4" too tall with the lid on to go into the stowbins. I finally got fed up of removing and re-installing the lid every time, so we bought a Q-100.
We had a behemoth 4-burner patio grill and gave it away. We use the Q220 on the patio now. We'll probably sell the smaller one, as we no longer have the RV.
I bought a 10-lb propane tank, the low profile "squatty" that has the same base ring as the 20-pounder. I got a tank base "spreader" from CW and bolted it down in one of the stowbins. Usually, I only had it refilled to half-full. It was retained by the spreader without additional restraints and never broke loose when driving.