I use TrackIR in 2-axis mode. Basically super mouse pan inheriting the hps file stored views.
That means if I want to use the gunsight I have to compromise between having some of it block my direction of travel view and being able to use the gunsight. With TrackIR holding slightly off center for a long travel time by turning the turret to one side is tiring and eventually disorienting to what the line of travel is. Lots of low buses and small trees have gotten to know me on some maps. Not to leave out gun emplacements who have trapped me or flipped me over.
I'm not recommending the turret turn with the observer\commander. Just a guy with the same zoom view as a commander and swivel head. Leaving the guns facing the line of travel will be enough instead of the red marker rotating in the circle.