The bypass valves are typically on the water heater. The easiest way to find them is note on the outside where the water heater is and look for a corresponding panel on the inside in that position (you may have to remove some screws).
Remember not to run the water heater until you know its full of water--especially when using the electric element for heat.
Looking at pictures here: https://www.rvtrader.com/listing/201...27.1-120191733
looks like the water heater is right behind the drivers rear wheel.
On your floorplan that would put it probably in/under the closet closest to the bathroom in the back bedroom.