Well, the weather has been lousy and I still haven't had a chance to try out this saddle. But I did decide to get a Cashel wedge pad to raise the cantle so the seat is level. The pad is made of closed-cell foam, 1/2 inch thick in front and 1 1/4 inch thick in the back and only around $30.00. In between the sheepskin and the saddle it should provide the necessary cushioning as well.
I also ordered a dressage girth with elastic on both sides, Wintec leather webbers (for less bulk under the leg than regular stirrup leathers) and footfree stirrup irons. All this added another $130.00 to the budget but if it works well I'll be very happy.