The links above talk about it, and it's basically the same principles as in riding a unicycle - if a guy is riding a unicycle, the CG is hardly ever directly over the point of contact with the ground. The forces generated by the rotating wheel are enough to dominate small shifts in mass and the thing stays balanced. I recall from dynamics class that it's the same math as ice skating where there is an infinitesimal point of contact (in theory). You can be forward or back on your skates and still stay up, like one would on a unicycle or like the airplane stays properly balanced.

The point being that none of these machines need a stab to keep them balanced and upright when the CG is within some reasonable range - so there should not be any load on the stab, and CG should not be trying to weight the tail down to increase the attack angle of the wings.