Tankless Water heater

If you are going to install anything, install a motoraid. Using the engine heat to heat the hot water gives you a great starting point. Once the water is hot, it tends to stay hot, and takes very little propane to keep it that way. The reality is, your propane water heater is able to keep up with any flow rate your RV can use. In some way it is already like a tankless, except you have to start with it hot in the first place. That is why I like my motoraid.