I used what @Rick Baggenstoss mentioned, a deer cam.  

The tenants pay above base rent with CAM to reimburse.

And that's like learning about sex from the other 12 year olds in the class.

Any recommendations on age, sex, likes & interests, etc.?

Just make sure there is enough of a CAM budget to cover all common area expenses.  

If the tenant doesn't have wifi, you'll have to run wires to a DVR if you're using analog cams, or a router/NVR if you're using IP.

Meanwhile, I think a big and easy to address issue is the cam lights.

@Brian Cam - Great idea! 

The couple upstairs that is man and woman can be late but not the same sex couple in building 2.That is why businesses have policies, so every tenant is treated identical because if not you open up yourself to all sorts of issues.

Also, you can get a wireless motion sensor security cam/monitor with phone app. and that you can actually talk into it.