Genghis (#1763),
We studes were told that the reason we were in the back was that, when our Instructor got out for our first solo, he being close to the CoG, the trim of the aircraft would hardly be affected.
Whereas, if he were behind and climbed out, the thing would be nose-heavy in the air and give us an extra worry (which you don't want on first solo).
But with a few hours under our belts, it should not worry us solo (but we were still kept in the back because we had no ASIs there - we thought all aircraft were flown "by the seat of the pants" until we had 60 hrs).
The Instructors had an ASI in front, so they never flew in the back !
I don't 'buy' the idea that a Stearman (or anything else) is better flown solo from the back. You can see obstacles on the ground (a R-22 for instance) and ahead in the air better when you're in front. I always did (so does Ewald, apparently).
It's a long time ago, now.
Danny.