Binger - agreed about painting. I'll paint it off the car. I did the rough construction on the car, but since then I've had it on & off dozens of times to do & check the finishing work.
Re. rear view: on a level road, I can just see the horizon below the edge of the Kammback with the rear view mirror adjusted normally. So I'm OK there. But I will get a pic from straight behind as well.
Edit: a dash mounted mirror is a good idea though - I could have made the extension even longer