The other problem was the weight issue. Look in the Pitts manual under the weight and balance charts, and you'll see that they stop at a pilot weight of 140 lbs. It turns out that the Pitts is designed so that with a solo pilot weighing 140 lbs in the rear seat, the airplane will be at the forward center of gravity limit. So the FBO still didn't want me to solo the airplane. The idea I came up with here was dive weights.
Divers wear lead weights on strong webbed belts to adjust their buoyancy.
The weights have holes through the centers so you can put a number of them on a belt. I had to prove to the FBO that they really were secure and brought in a bunch of engineering specs on the dive belts that I got from the store. I think there's too much risk in having weight like that loose in the airplane. I'm just mentioning it as a possible idea. Finally, under G-loads the cushions would compress and I would again have trouble reaching full rudder extension.