My Owner's Manual from the RV factory was almost useless - only a page or so. But the important info was in the Owner's guides for the various appliances and options on the trailer. AC, water heater, range/oven, awning, microwave, power distribution box, reefer, stereo, axles, tires, etc. Those thin Owner's Guides were all inserted into the RV Owner's guide.
Plus my RV dealer wrote a several-page brochure explaining all about RVing and setting up and towing, and he included that brochure with the RV Owner' Guide and all those appliance and options guides.
Of course, if I really need to know something about my Sunline Nomad Joey Model 196S, I use the internet and a Bing search.