there are manuals out there, you just have to find them. I have the manuals for my 91 camper, my buddy has all the manuals for his 1972 frame mounted camper. if you are hoping for wiring and plumbing diagrams thoes you wont find in the manuals, they are just a real basic info on operation and care, and the apliance ones are just about the apliances.
I found a wiring grembling with my camper where for some reason all my lights work except the hazards so somthing isnt run right for newer vehicles. I am almost at the point where Imay just rewire the whole thing and make the lights a seperat system from the camper internals. I don't use the charge from the truck so it isn't a big deal.
Steve