[Koha] Can I limit the opac to see only the main library?

We have a group of books that only certain people are allowed to check out. At first we were thinking of giving these books a different Item Type, but maybe they should exist in their own new Library. I think making a new library is a better plan. But what about the opac? We don't want them showing up there at all, because regular patrons won't be able to sign them out. Is it possible to limit the opac to see only the main library? Thanks. -- Tim