I used one of those when I built my custom seat 15 years ago. Worked great! Though the outfit that sold it to me stopped selling them so that source is gone. See
http://www.horseapple.com/Valkyrie/Tech_Tips/Rood_Saddle_Mod/rood_saddle_mod.htmlI sold that seat as I got a great buy on a complete Mustang set - should have kept it, was a great seat. Well the guy who got it, I'm sure his butt is happy.
Later I got an Ultimate Big Boy which I still have - put an Alaska Leather sheepskin on it for summer (hot) riding, or any distance. Most of the time I use the wing for distance riding. Butt's not happy though. I'm fixin on getting a Russell if I keep the Wing.