Freedomvan,
Northwest is a pretty open geographic region....
As you have discovered, the companies that do RV sales and service will only service what they sell. They are not interested in restorations.
If you are near anything urban, look up the local community college(s). One might offer some courses on RV maintenance.
If that plan crashes, get what books you can out of the library or go the FMCA site and look at all the information that they offer for RV maintenance. If they can effective tell you how to maintain the system, they have to describe how it was initially assembled.
I wish you luck in your plan.
I was forced to stop being a workaholic and it was the best thing that could have happened.
Matt