Most people make the error of using a saddle that is too large for their model.
The saddle is basically only there to support the rider's leg, and there isn't much leather not covered by the rider. The difference is less in the amount of leather present and more in the angle and length of the saddle flaps. I've drawn lines showing the relation of the end of saddle with the horse. Most model horse english saddles are too big. Take a look at the photo featured in this issue's Judge's Corner.