Unfortunately, you're probably going to have to use trial and error. The twist of the saddle may be crucial for you. Although I have no hip/back issues, I haven't been able to find a Stubben I'm comfortable in. I've tried a bunch (luckily, having a boarding stable, I was able to try a lot of makes and models.) I think they're beautiful, and last forever, but there is something about them that hurts me. I also couldn't use the two Schleeses I tried, but they were custom-made for other people. I absolutely hated the treeless saddles- no feel what-so-ever. There are come Coubettes I can ride in, Crosbys are good, Antares are nice but seriously over-priced IMO, Bates and Wintecs OK. The one make that seems to suit me best (to date, anyway) is Kieffer. I have a Rhein dressage and a Munchen AP, and can ride in either comfortably all day. The Kieffers have a fairly narrow twist, which I guess must suit my conformation.