I can only comment on the foul smell issue. We discovered in our new (to us) 2006 Fleetwood Pace Arrow 37c that anytime anyone used the toilet, especially #2, there was a foul smell coming from the black tank. What I came up with was that since there is no trap below the toilet and the toilet dumps straight into the black tank and the water in the toilet is the seal.....when people use the toilet, naturally we would all turn the fan on. Well...with the fan on and flushing, thus breaking that seal, there would be an inrush of the black tank odor filling the bathroom. New rule: DO NOT TURN THE FAN ON UNTIL YOU ARE FINISHED. Since its a fantastic fan, it vents the bathroom very quickly. This new rule has prevented unwanted odors from coming up into the bathroom from the black tank.
Otherwise......I enjoyed your narrative even though I know you were probably frustrated through all that!!!!