Interesting really.
Was the German aiming system a one-eyed system??? Really don't know,but somewhere I have a pic of a German pilot looking through the sight and he is just using one eye.
Anyway, once one has had years of rubbernecking,one will be able to turn the head backwards much further to one direction, typically to the right. Ask any farm-machine operator. A long day may leave you rubbernecking up to 5.000 times. Belive me, that leaves your neck hurting, and a burn wound from your collar. Just what I have read from pilots accounts!