Are you able to throttle down the exposure level on that camera? In our experience, if you can't do that then you won't be able to get good green/blue/whatever color values off the reflective tape from your LED ring (assuming you use one). Without exposure control the tape blooms out to a near-white value, making it very difficult to isolate that separate from the field lights.
We use a Logitech C920 on a RPi2, and had to dig up an old command-line program that supports fiddling with the exposure settings. The consumer-grade utility Logitech ships these days (the Windows one with the GUI) only works for that session, and only on Windows of course.
Once we had exposure under control it was pretty easy to get reliable target isolation using GRIP. The sunglasses tip is interesting, hadn't thought of that.
