Sometimes It's Just Easier To Flag Your Camera
One of my favorite ways to shoot is with accented rim lights. And while I love the look this kind of light produces there is a bit of a trickery to setting those lights up.
The reason is that back lights create flare.
While I have never tested this, I would imagine it would need to be a biggish frame to block lights coming at a wider angle, but even a smaller flag will help to reduce any flare coming from roughly camera front.