Hot Water Recirculation Loop - Save Water - Camp Longer

First, I have installed a recirculation/conserving system in my campers since 1995.
Second, the water should return to the cold holding tank. If the water was hot at the faucet you don’t need to recirculate it. The reason to recirculate is to get hot water to the faucet and return the cold water in the line to the tank,
Third, I use a cheap inline irrigation valve ($10 to $12) and a $2 doorbell button. No need to go to specialty valves and pumps.