Backplate riveted the rudders trailing edge.  I have not been able to find any pics of this on the net.

After dimpling both skins and countersinking the wedge a good bit there were a few places where the three

parts don't lay perfectly flat.  Although the entire edge was perfectly flat and within the .100" limits. 

Overall I am very pleased how it turned out.

The rivet doesn't fill the entire dimple but this is how it should look using a 3.5 rivet.