I've dealt with these only in residential and sticks and bricks commercial installations, and have found them frustrating, because they have to be rather closely matched to water flow. Too high a flow, they don't keep up; too low a flow, and the water gets too hot, then suddenly too cold, as the device shuts off as it tries to control temperature. I used one in a kitchen sink installation that went on to produce steam before backing off.
A RV specific device, matched to RV water flow levels, should work OK at maximum RV water flow. I've not yet installed and tried one of these in a RV.