Well, I think the sneakiest part is actually going to be for the teachers. :/
I mean it's university. It's large and here at my school students can get up and roam out anytime, no one cares, too many students to ask why, and with all the other students who come and go anyway, not related to us but who'll be doing it anyway, it shouldn't look terribly suspicious. The teachers though, they'll have to make up excuses to be leaving all the time.