Finished mounting the right rear wingtip rib. Also split the wingtip a bit further to adjust the fit. After I was satisified with the alignment I preliminarily glued the cuts with a mix of epoxy and flox. Went on to mounting the left wingtip. I trimmed the tip to fit the wing and drilled the top and bottom mounting holes. It appears the left tip fit is much better. Probably just a result of me aligning the tip better.