Sargent Seat Fits all 800 Scramblers..... except Full Throttle, why??

I have a 2018 Full Throttle, and the stock seat kills me. I bought a stock seat for an Icon which was a little better, but still hurts me. I then bought a Mustang seat, but I hated the way it forced me up against the gas tank, so I sent it back.
Sargent Seat was recommended to me, but theirs excludes the Full Throttle.
Since the Ducati seats, Mustang & Mugello seats fit all 800 scrambler models, I asked Sargent why was the Full Throttle was excluded. 3-different people at Sargent gave me a generic answer that "it just won't fit". BUT, when I ask why, they can't give me known valid answer.
***Anybody on here know why it won't fit the Full Throttle??
This is my 18th motorcycle, and this is the only bike I've owned that hurts me so bad in just a 20-mile ride.
I also have a Vmax, which are not known for comfort, but I can ride it ~150-miles before it starts hurting me.