His build does not do us any favors. He is capable of dropping his back about six inches below his withers. Even with an appropriately fitting saddle when he drops his back like that it automatically tips me so my legs slide forwards, my upper body comes forward, and I grab with my hands. Obviously this causes him to drop his back even more and it continues until I get my shit together and remember to ride.
Even so, we are slowly getting more consistent. Yesterday was a bad day, but we still managed to grab some nice moments. He still curls behind the vertical when he lifts his back, but again it is more of a strength thing. He just doesn't have the muscle support to properly carry correctly for very long.