Propad.
I've had beads, AirHawk, Sheepskin... shit, I've even made my own from the orthopedic cushioning we have work... nothing worked. Til now.
I picked up a ProPad off the Connie board for $75, and haven't looked back,. No butt bone pain anymore! Even on the GL1800 I had pain... but with the ProPad on my Corbin on the C14, no complaints at all.
Medical grade gel pad in a sheepskin cover. Nice and firm, but pops off in an instant if you like.