Yes, that's a good idea! Though I expect some correcting optics would be required to ensure the stereo scanning beams won't point out radially from the screw, but will converge on the subject.
Just as I thought I'd got on top of this at last, and achieved what I'd wanted, it's beginning to look like I'm not going to get a rest after all...
Next stop - to make a couple of mirror screws. One for the stereo camera, one for the monitor. Taking into account the angles etc., what would you say is the maximum practicable line count for a mirror screw?
Steve