It would be unusual to not have at least one drain each for cold and hot water circuits. Whether or not there is a yet another drain for the supply line to the water heater would depend how lines are routed.
I have three: one just downstream of the water pump drains cold water supply to outdoor shower and water heater. A hot water drain and a second cold drain under the shower drains supplies to bathroom, kitchen, and shower, and works pretty well to siphon water from the water heater.
I take it Forest River does not supply plumbing and wiring diagrams for each model?