Very few horses need custom saddles, but most horses need a saddle that fits them. Who are you working with?
It’s hard to tell from your photos but just at a glance it looks like a fairly normal back and shoulder for a sport horse - long and tall wither, wide shoulder, a little short in the back in terms of where the saddle can sit,there is nothing that screams “I need custom dimensions”. Kind of looks like an average TB back to my eye.
I went through the ringer with something similar years ago when my favorite saddle fitter moved out of my area. I tried so many saddles from local reps and fitters, including a custom Stubben. I wasted a ton of money and time, and unfortunately for one of my horses, he required a fair bit of veterinary intervention after being too kind/generous to tell me his saddle was really messing up his back.
I finally emailed my former fitter (the one I mentioned above that moved) and begged for a remote consult. I regret not going this route in the first place – I know, “remote consult” seems so counterintuive when it’s beyond valuable to see the horse in PERSON – but when you are surrounded by crappy fitters (as most of us are), sometimes it’s your best option. I sent her wither tracings done by multiple reps. I’ve used her remote consult option twice now, and I know she knows what she is doing because I have two horses who have long time saddles selected by her - one has one that is ~8 years old, and the other is going on his fourth year with his. I’m using her right now for my filly - we’re in the process of trying a few different ones. Give her an email or a call if you’re in the states:
Patty Merli
(843) 810-2485