What about going from 17mm to 25mm stub axles. That should increase front grip too. Will it help with rotation?
Seat placement – I installed it so he can see properly and reach the pedals, with no other science involved. We scaled it at 43/57. I also welded tabs all over the place so I can put weights anywhere to get it corner balanced. As it turns out, he only needs about 10 lbs of weights, so only have 1 7 lb weight on the back of the seat, and use the fuel for the rest.