Hi Merlyn,
I was having the very same issue on my '04 Heritage.
Including the stocker, I went through about 4 seats (HD, Mustang, LePera, etc) before the problem was solved. Now, this isn't intended as an endorsement, but (pardon the pun)... After a little research I decided to try a Corbin seat. Corbin seats aren't very soft to the touch. And when you first sit on it, it feels wicked hard. But the more time you spend riding with it, the more comfortable it gets. They are quite a bit wider than other seats, which is the secret. Like they’re product description says, it helps to eliminate all the pressure points, and over time it forms to your shape.
Used to be after only 1 hour of riding my butt and tailbone would have me almost screaming in pain! Now, I can go literally all day (like I just did Saturday & Sunday) with no discomfort at all!
And no… I don’t work for Corbin or anything like that.
It’s just the truth!
Hope this helps!
-Caveman