Originally Posted by
slowandsteady
It ain't rocket science, and you don't need a picture. If he is sliding forward, then the tilt is off. Tilt up slightly until you find the perfect angle between not sliding and not squishing delicate parts.
OP didn't say he was
sliding forward, just that his butt "winds up there".
If the only thing that hurts are the sitbones, then by moving the saddle forward, the only thing you are changing is where the sitbones contact the saddle.