Dave Hamblin
(formerly DaveH on old site!)I can say the visibility from the front seat in an S2B Pitts is basically "none", but also for balance it must also be flown solo from the rear.
If you think about it, thats the best "consistent" spot for the pilot (rear). The passenger sits closer to the CG in the front, so has a less effect than a rear seated passenger. If the plane were balanced with a front seated pilot, think of the CG shift when a passenger got behind him. In front, it does shift, but not nearly as much.
Just my two cents of thought. By the way, through my RC airplane hobby I have first hand seen how a plane (doesn't) fly with an aft CG. Quite spectacular.