Have you taken a look at any used saddles? I used to check endurance.net classified back when I was looking to buy.
I always liked the look of the Sharon Saare's. Their fitting system is very specific as well. Home page The Synergists also have a very specific fitting system. I liked the Desoto too because of the specific fitting but I thought the angles too flat so it may be more to your liking.
The Long Rider's Guild has a nice equipment information page with comments from folks riding long distance. Plus it's just an interesting site with great stories, if you haven't perused it already. Hope it's ok to post other web sites here
Those are just a few that I looked at for a custom fit type tree. I'm sure there are many more. Good luck in your search, hope you find that perfect fit. It is out there