Hotel Dieu Hospital
166 Brock Street, Kingston, Ontario
100% positive
Directions: Hall on your left when entering from main entrance/lobby (next to the cafe).
Comments: Multiple large, private single stalls. Of course, this is a hospital, so it is intended for patients and visitors, but if you just slip in, it's usually busy enough that no one would notice or bother you. Just be considerate of the other patrons (i.e. don't bring your whole friend group in with you, santitize your hands if you can, ect).