Congratulations on your RV. Owner's manuals are general in nature to cover various models and options. You could look at other maker's manuals to see what they say about certain procedures. Manuals are often hazy on location and connections of various things like valves and wiring. Winnebago, Thor, and others have good documentation online.
An engine/chassis manual should still be available from the manufacture. For example you have a Class C motorhome built on a Ford van chassis you can get a manual for that year chassis from Chilton or Haynes.
Spend some time going through every access compartment, cabinet, and closet. Note the manufacturer and model of each item you discover. Then sit down and Google each item followed by the word, "manual." You'll find many companies have manuals available online you can link to or download, making your own reference guide.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI