I say keep the sight where it is historically but allow to switch to sight view with pressed button. I proposed a solution that me thinks does the trick and still sticks to realism as closely as possible and should allow still the immersivity and allow nonetheless to have realistic aiming with 109 sight. And it would even allow people who like the current way to continue.

Solution:
A button push should save temporarily the current head position like shift+f1 in old IL2. As long as this button is pushed this new position is maintained until the button is released. Of course head shake and g effects would be still working. So for aiming I would have to lean to the right finding the good position for aiming (which could be also quite difficult in the outcome), I press button and keep it pushed. So now my head position is locked to this saved position and I can view normally as I would with normal centre head position. I now have to steer and shoot while keeping the button constantly pushed (not THAT easy to do) in order to stay centred on sight. When I release my head will jump back to cockpit centre position. If you prefer the old ways you still could just lean right.

Those people shouting that this would dump down realism just don't understand that this thread is there because of available computer hardware which makes aiming with 109 currently absolutely unrealistic.