chopjock,
Can't move the bolt hole. C of G needs to move forward relative to the aero foil section. As the picture shows, there is plenty of room in the D-spar to drill a hole and place weight.
I'm thinking the best solution is to gun drill deep 3/8" or smaller holes in the D-spar root and tip, insert the proper weight of tungsten rod to bring the CWCG to 24.5% and use threaded plugs to hold the weights in. The root and tip weights could be adjusted in ratio to move their virtual mass spanwise to 70%.
Mike