Ive only made a couple saddles so far so take this with a grain of salt.
i did a basket stamped cantle back with a single border running across the top.
I molded it to the cantle marked and trimmed for my cantle binding. After trimming i reinstalled and then marked where the binding is going to be. After that i took it back off. It still had enough moisture so i didnt have to recase. I marked i think 3/8ths in for my border. Tooled my border along the arc and then basket stamped all the way out to the end of the bottom. The jockeys covered the bottom. I think next time ill rough fit my jockeys and then make the border on the bottom as well.