Joined: Dec 2004
Posts: 12,561
Likes: 799
From: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Bacchetta Quattro, Catrike Speed
If the tailbone area isn't structural, you could cut relief in the shell. Performer does this to their FRP seats, I believe.