Provide a plywood former in front of wing ld.ed.to drill hole for 1/4 inch ld.ed dowel. Securely glue (epoxy) rear bolt mounts. I prefer to use hardwood blocks on each side. Then using proper size drill. Drill holes for taping 1/4-20 nylon bolts for rear attachment.through wing and hardwood blocks. Tap hardwood blocks. Use some thin Ca on threads after taping then run tap thru again after ca hardens. Next enlarge holes in rear of wing to clear 1/4 inch bolts, good forever.