Wingstands were factory attached to the wing using wellnuts. They're rubber with a brass insert. They just push into the hole and when the screw is tightened, the brass insert pulls toward the screw head and causes the rubber to mushroom inside the wing. Years ago when I repaired one of my wings, I had the same problem. I just cut the screw head off and let the other end fall into the wing. This is what it looks like. Just push the long end into the hole until the shoulder is flush, place the stand on the wing and insert a screw and tighten.
The wellnut part number is Au-Ve-Co part number 16248. GM part number 14005097. Use a stainless or brass screw, but if you ever have a problem removing them, just grind the head off and push them into the wing. I wouldn't really recommend putting in nutserts or anything permanent like epoxy or J&B Weld to hold things in place, since the wingstands are prone to breaking and may later need to be detached from the wing.
[This message has been edited by fierofool (edited 08-03-2013).]