I think you should check with a local dealership, and ask about the solar pre-wired thing. They might be able to sell you a water tight plug to fit the connection on your roof, if your model year included such a connector.
And show you where to look for the wiring in your RV. Yet I would avoid having them install it for you, it is not all that complicated, it only took me about 3 hours to install my solar system, including running the wiring. 3 hours shop time in many areas would run well over $300. Might as well save the labor costs.
Good luck,
Fred.