Welcome to the asylum!
Aside from rebuilding a generator housing, I’ve tackled everything you’re about to face, including replacing a rotted floor caused by a small but hidden leak in a water holding tank.
It might seem like a major undertaking, but with a good workspace and a willingness to invest time and effort, you can be very pleased with the results. Start by removing and replacing the floor. I chose to replace only the damaged section, making precise saw cuts to fit and secure the new piece to the frame members. Since the foam insulation was still intact, I bonded the new marine plywood to it and then screwed it into the frame. I finished by covering the floor with glued laminate and sealing the edges with RTV.
I also rewelded the entire water tank and pressure-tested it before reassembling the bay. While everything was apart, I inspected and replaced any questionable components. For my current coach, I upgraded to a stainless steel water tank, added thermostatic control for the engine coolant through the tank heat exchanger, and installed a backup water pump. I modified the primary water pump’s pressure control to allow higher water pressure in the house system and added an over-pressure shutoff. I updated the piping, added service valves, and replaced all rubber hoses with new ones. My bus is the same age as yours.
On the waste side, I modified the macerator discharge to share an outlet with the gray water bypass and reconfigured the cleanout hose fitting. It might sound like a lot, but with a few tools and careful work, you’ll be happy with the results. The water bay is one of the simpler parts of our coaches, and to my knowledge, none of them have high-tech systems that require special skills or tools.
Remember, most converters do a great job designing logical systems. Before making major changes, get to know your setup and understand why the engineers designed it that way. You might find that small, simple modifications could be more effective than a complete redesign. I’ll leave it to Royale owners to share any specific changes they recommend.
Have fun with your project!