He's a dutch warmblood, with average withers and I would say (from eye), a medium width. Whenever I don't ride him, I ride Coco, a TB. For a TB she doesn't have huge withers, but they are high and she is of course, narrow.
I want X to be the horse I really ride almost all the time, so I want to eventually get a saddle that fits him. However, if I ever ride Coco, I know I'd have to add a pad/half pad to make up for the extra room. (That's what girl at my barn does with COco because all the saddles are of medium width). She had a half pad and the saddle fit so much better and it was really comfortable to ride in (I had a small lesson on Coco right after her ride on her).
But if the saddle is for a average withered horse, and I put it on a high withered horse... what becomes the exact dilemma? AS in will the saddle tip back and put pressure on the back or something?