Looks to me like it would be better to plug that hole with flox that to install some of those micky mouse hinges on the controlling parts of the plane with rivits. Any hole in the spar is going to weakin it some. but how much. If I did rebuild it I would darn sure stress test it just to see what it would handle for the next time I messed up! There has to be a good fix. Maybe rap it in carbon fiber or a couple layers of glass. Shoot just by looking at the pictures,those firewall mout brakets and landing gear mounts look more fragile than a small hole filled with flox to me. I guess thats the way it is with planes. By the time I got one built it would weigh 1500 lb's.
