only one low point drain?

keep looking might even be a set of valves somewhere

Look near where the HWT is, or the water pump. It sounds like you have found the fresh water tank drain only.

Our hot and cold drain lines have valves inside and, obviously, drain to the outside.

Just to clarify - the fresh water tank has an on off valve inside which drains thru one clear plastic line. However, next to the drain hose is only one more plastic drain line with a cap on it.

So I have two drain hoses under the MH - the identified water tank drain and the other one.

Our previous Class C had a "Low Point Drain" label on the kitchen cabinet they were located in. That was for the Hot and Cold plumbing. The coach we have now, has that label on the outside compartment where they are. Again, Hot and Cold. Then I'd expect to also drain the Fresh Water Tank and the Water Heater. Let the water drain out of the hoses for your Shower and Outdoor Shower.

If you're expecting a deep freeze, be sure you blow out the toilet flush valve, and pour the water out of (or RV antifreeze into) any traps you have. Typically Kitchen, Shower, and Lavatory.

It's certainly possible that there may be inside low point drain valves that both connect to one hose via a tee on the outside. I don't know that it's common, but there's no reason why such a design is impossible.

I'd personally be more concerned with finding the drain valves. If you open the cold low point drain valve, and water comes out somewhere underneath, and likewise for the hot low point drain valve, I don't really see where it matters exactly how or where it comes out.

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?

Look in front of passenger side rear wheels in wheel well.

My Winnebago "C" has two valves in a storage compartment on passenger side rear that drains the low point drains.

Our Greyhawk has only 1 low point drain. The hot water heater drain plug is lower than all other hot water lines, so no need for a separate hot water line low point drain.

-Michael