Rear bolts in!
Front bolts in!
You may have noticed that I have done nothing to reinforce the leading edge where the bolts pass through - that's because I really didn't want to open up the wing to add reinforcement. The sleeve prevents the bolt from crushing the wing, although it is only attached by epoxy to the upper and lower skin in the wing. The little voice in my head, which I do try to listen to, told me this was a likely failure point. I decided to try it anyway. When the front bolts were in, I picked up the plane by the wing (near the roots). It held. I tossed the plane a few inches up and caught it by the same place on the wing. It held. Success!
Alas, when I attempted to bore out the sleeve just a little bit for the bolt to slide more easily, the bit torqued the sleeve a little too much, and the little voice was proven right.
Nothing for it now except to open things up.