Well, let me see.
I spent thousands of dollars on a saddle which was short from front to back (Pegasus Butterfly jumping saddle), I was looking at other saddles but my choice was easy when I learned my riding teacher wanted me to ride this horse. I also use a Contender II BOT/ThinLine saddle pad with two bridging shims on each side.
I ride him 30 minutes, usually now just once a week.
I ride Forward Seat. It is absolutely no sweat for me to get my seat bones forward as far as I can, which is helped considerably by how this saddle is made.
If I feel distress from the horse I get into half seat, putting my weight forward, off my seat bones.
When that is not enough to make his back relax I get up into two point until his back starts swinging.
It may take a few minutes, but usually eventually when I sit back down in the saddle his back stays relaxed and swinging. If his back does not improve I get back up into two-point until his back “invites” me to sit down again.
Some rides I spend A LOT of time in two-point.
After we take the saddle off I scrub his back with the HandsOn grooming glove, pretty hard. He LOVES this, so the saddle just does not seem to hurt his back. Believe me if this horse hurts from something he makes sure the everyone around him knows about it.
When I started riding this horse he was an inverted balking mess, had an iron hard mouth, he backed up compulsively when he didn’t want to go somewhere, he had no true understanding of rein, leg or seat aids and he would LEAN on the reins. All this has changed, he has not inverted for many, many months, he strides forward freely, he willingly reaches for contact and now he responds to light, well timed rein aids (and my leg and seat aids too) and he only backs up when I ask him to (used to be his favorite defense against his riders.)
And yes, he still has a sway back. He is around 25 so this is not going to go away. I just ride him the best I can, I care deeply about his comfort, and this horse who used to try to disobey every command now cheerfully obeys my aids.
He is turning into a really neat little riding horse. He cannot help it he is one of the ugliest worst conformed riding horses I’ve seen in my life. The scowl that used to be on his face all the times has now turned into an expression of interest and he likes people a lot better than he used to. He even nuzzles me occasionally while I groom him.
And all of this is done under the eyes of my riding teacher who asked me to work him in case I could come up with some miracles. No miracles so far, just humane Forward Seat riding while accepting his considerable conformational limitations and a short enough saddle for his back, which has led to a MUCH more comfortable horse under saddle.