Our Coachmen was a new dealer purchase, so it had a stack of manuals with it. I bought a bunch of the clear plastic sleeves and put them in a big 3 ring binder and stuck them in a cabinet inside the TT. The new owner of the Coachmen really appreciated having all the manuals. I'll likely do the same with the new KZ MXT when it gets here. As for a Make/Model specific RV Manual, like others have said, most don't really do one anymore. It's more of a general overall "This is an RV" type of manual.
It's also a good idea to keep an electronic copy if you can find them to download. I have an entire file on my computer with Pics, manuals, diagrams etc for damn near everything.