See the attached photo of my bathroom darkroom - note that the entire 4' x 8' wall above the vanity is a mirror. The Beseler enlarger pictured is now in storage and an Omega D6 on a really large cart is in its place, but otherwise what you see is what I have been using since I started on APUG.

The mirror is only a problem if you have too much light in the darkroom in the first place.

If I had to have the enlarger right up against the mirror, I would cover a portion of the mirror, but it is six feet away. I get fog free results.

There are two doors into my bathroom. I've put some light, easily removable, weather stripping into each opening, and I block the area at the bottom of each door with a rolled up towel.

When I am loading film into cassettes or on to reels, I am careful to check on whether incoming lights are fully blocked. If I let my eyes acclimatize, I can perceive a faint lighter area around the doors, but I cannot see anything else in the room, and I always load film with my back to the door. I have had no problems with light leaks or fogging.

When I am printing, the doors alone block almost all the light. The towels and the weather stripping are only really necessary on sunny days or when I have all the lights turned on in the rooms outside the bathroom. Here too, I have had no problems with light leaks or fogging.

With a reasonable amount of care and attention to detail, you should be fine.

Have fun - I certainly do.