It was fairly easy installing the rear spar bolts and torquing the castle nuts but installing the cotter pins was another story. There is not much room between the side of the fuselage and the inboard edge of the wing to bend the cotter pins but I was finally able to manage with some long needle nose pliers.
Right wing rear spar bolt torqued and cotter pinned
Left wing rear spar bolt torqued and cotter pinned
