Most manuals are fairly generic. Go through the camper, write down the info from every appliance and add ons, do the google, print out each manual and put in a notebook. Same can be done for axles, tires, jacks, etc.
You will end up with a better manual than any the manufacturer would have.
Oh, get a large notebook. Youโll need it.
Kip
2015 Skyline Dart 214RB
2018 Silverado Double Cab 4x4
Andersen Hitch