Well you have likely figured out your problem. When the hot line output check valve becomes frozen with calcium deposits no (or very little) hot water flows out of the tank. Attached is the first Youtube video I found that might help a little "generically"with replacing the check valve. Just make sure you turn off the hot water heater switch (electrics) before you drain (empty) the tank and don't turn it back on again until after it is full of water and you have pressure tested for leaks and proven the new check valve has solved your problem of water flow from hot taps.
I am not sure exactly where your water tank is actually located, but on the exterior there is only the two heating appliance exhausts....furnace and hot water tank. Furnace usually has a screwed on panel; hot water is typically a metal tab you turn 90 deg which allows the access panel to be opened. Gives you a rough idea where the hot tank is located. Of course the check valve is accessed on the inside of the coach on the tank, which is probably behind a removal panel or under a removable drawer etc. It may be near your winterization hot water tank bypass valves if you know where those are located. Someone with your coach may be more specific on how you access the hot water tank from the inside.