Well as you can see here:
...the canopy extends out left and right in "wings" near the gunner station. And if you look here:
You can see the gunner's station. Ignore the pistol grip, it appears it's folded when not in use. Note the gunsights in each "wing" so that as you tilt the guns down you can still look down past the fuselage. [EDIT: I don't know what field of view you'd get, but the intent for the 410 was to be able to fire below the tail] The outer sights are also inverted to avoid getting in the way when looking down. When firing up you can use the central sight.
I proposed one idea to HTC regarding this. Make it 1 gun stations but with 3 gunsights. You can only see the gunsight when centered on it, so the default head position is where you'd start. Then you slide your head left or right until that gunsight is now your new aiming reference. Because of the reflector nature, as long as you see it on the glass that's where you are aimed.
It was just one idea. I wouldn't mind a left/right setup if that's what they give us. I hope they come up with a more interesting way, though.