I recently replaced my on-demand water heater with a tank model because I absolutely hated it. It is the worst thing to have in an RV that is used for boondocking.
Taking showers was a joke as was the "hot" water available in my bathroom sink. To get hot water to wash dishes was a pain. I would first have to run it on full blast and then throttle back to get the temp up. I had my heater set at the max of 124 degrees but that never made it to any outlet.
My tank water heater is oh so much better. I can burn my hands doing dishes. Hot water now can get to the bathroom sink. Showers are noticeably better. Best of all you don't waste as much water, which is a concern when dry camping.