Don't put too much effort in trying to find the manual.
I bought a '98 Gulf Stream Sun Voyager and I was pleased to see it had all the manuals and information in a big official looking binder. Reading it cover to cover, it was mostly the individual installation directions for each system in the rig. I have an issue with the house battery shut off, it doesn't work. The manuals and wiring diagrams don't give a clue where the actual solenoid is located, I still have to search.
The information contained in the binder is mostly the installation instructions, little about how, when, why each system should be operated. The Gulf Stream instructions are CYA cautions and idiotically simple things as found in most bloated auto owner operator manuals.
I've also googled the different manufacturers of the various systems and downloaded .pdf files of operating instructions when possible.
I've learned more reading this forum than anything the documentation contained.