I am away from books, but if I recall correctly, part of the reason for building a Laboratory is to stabilise the local magical flux (for want of a better term), so it won't disturb delicate magical operations and the such.
So would it be possible to create a ReVi ward that calms the local magical flux? Enough for minimal Lab activities, like learning from books or teaching an apprentice?
Just wondering about Magi on longs trips, who want to do some studying when rhey are camped.
You don't need a lab to learn from books.
I don't remember anything about needing to stabilise "local magical flux", either - I think it's more just that you need certain equipment set up in particular ways, which ideally needs to be properly protected.
Neither reading books nor teaching apprentices are lab activities (that is, neither requires laboratory space and neither involves a Lab Total), though the Covenants lab rules allow labs that give bonuses to the latter.
By the same extended rules (Covenants 122), a non-ritual ReVi ward would actually add to the "lab"'s Warping or subtract from its Safety.