I have finally given up with the pop-in/fall-out tie-downs in the wings of the L-IV.  Has anyone come up with with a better system?

The one solution that comes to mind is tapping some threads into the tie-down receptacles already in the wings.  Unfortunately I cant determine the wall thickness of the receptacle because my paint makes this impossible.  If anyone can tell me the wall thickness of the standard L-IV tie-down receptacle, I would be very grateful.  Regards, Bill Hogarty