I think a good compromise would be to work it like the bomb site in buffs. F1 is normal view, without the gun site or aim point reference; you could still traverse and elevate the gun and fire it, but without a gun sight you'd be unlikely to actually hit anything. F6 would drop you to the gun sight, with it's aiming reticule and zoom, but no ability to look around. My 2 penny's worth.
