Water too hot during Navy shower

I solved both the hot and cold shower restart issue (two different motorhomes) by installing check valves where the water lines connect to the shower faucets. The problem occurs because one line or the other has a slightly higher pressure than the other, probably due to upstream fixtures, so when you turn off the shower head valve, the higher pressure line forces its source back down the other line for some distance until they equalize. The check valves prevent the backfeeding. I used PEX check valves from Watts/Sea Tech that required just cutting the lines and pushing the ends into valve bodies. Just make sure the arrows are pointing towards the faucets.