Rechecked measurements and made some final tweaks. Backdrilled to extend the pilot hole on the rear attach point through the rear spar on both wings. Detached wings from fuselage to get a good look. As I suspected, there is not a lot of edge clearance if the pilot holes were to be expanded to the full AN6 size. Time to shoot Roger an email. From looking at the blogs, this is not an uncommon issue and Zenith may have a rear spar extension fix.
