[*Anya*]

Having worked in offices forever once I left hospital nursing, I have found out that: I too hate to have people walk up behind me. I am in the first office set-up now in which the desk configuration is loopy and the door opens behind me. I had my monitor set up off to the side so I could at least see part of my door. Can your monitor be positioned any differently?

Would it be possible to ask your co-worker out to lunch or take a break with her or bring in a cup of coffee for her in the AM? I find people are much more responsive if I am self-effacing, i.e., "I know it may sound strange but the mirror is just a quirk of mine because, etc". People are usually more workable if they understand. It's always worth a try.

If she had been there longer than you and you have no senority, if this could impact your job, you could think about talking to your direct supervisor about it because you do not want the co-worker to go to HR and complain about it and get them involved.

Or if you try everything. Take it down. It's easier to make a stand at a job (reasonable accomodation) when you have been there a while rather than as a new employee. Employers don't like hassles these days but only you can decide for yourself the best course of action.

Best of luck