There is another way to balance a mid wing that is less sensitive than using a balancer on the wing.(my Showtime 90)
See my picture, the hole in the cross member that is glued in at the target CG has a blind nut so I can screw in a small eye hook, I hang the plane from that hook. The cockpit is balanced seperately by moving the pilot around so that is will not change the planes CG when installed.