Trev, I got all excited when I read the aluminum rib idea. But then I remembered that there isn't a rib at the point where the cabanes connect. Oh well... maybe I can use that idea on the interplane strut connection.

Bob, the spar (which is of the box spar type) is only about 10mm wide and I'd have to drill a hole at least 4mm. Maybe I could wrap it with glass first...