Kind of hard to see clearly. Photos aren't so clear. Anyway, it looks like itmight be ok. There's hint of maybe being a bit narrow at the front part of the tree. Really hard to tell without being there to run my hand under it. The angle looks maybe a bit steeper than the angle of your horse's body, but again, I am NOT sure from these pictures.
That kind of dressage saddle is closer to an all purpose in the fact that it has a forward angling flap. In fact, looking at the d rings it has on the rear, I wonder if it actually isn't an AP?