Oh geez, so he is probably short backed too in comparison for the length of tree and skirt length.
If so, same here, very short backed and just round skirts does not remedy the hips shoving the saddle forward.
My husband has wanted to expand his leather working into saddle building. And having a few friends that are excellent saddle builders we are going to try a LaPort tree and with guidance build a saddle.(they figure with tree and leather for price to be about $700) To be honest, normally we would never spend the money or energy, but we believe her to be a great mare that loves her job and works hard. So we may just try it...
I DON'T LEAD 'EM AND FEED 'EM, I RIDE 'EM AND SLIDE 'EM.