Char rigging fine points.

Okay so i’m making some robot character models, my first one is a skinny skeletal one and because he’s so skinny I’m having trouble fitting him to the standard biped:

as you can see the bone (on the left) is quite far away from the ball joint on my character (right) this means that the pivot is off dramatically and thus my ball joint doesn’t work, as the top section is pivoting off of that bone, the effect is too ugly to post.

What I’m wondering is how much you can get away with editing the standard skeleton until it can no longer be used with male character animations?

alternatively is there a way to make it so my ball joint works without moving the skeleton?
Thanks for reading <3