Hi Dan,
I fitted the wing to the body, put the donut in place and used two servo screws to hold it in place. I had already drilled the two holes in the donut. Eventually I will replace the servo screws with two M2 nuts and bolts.
I also made two of these linkage covers from some 2mm balsa one night when waiting on the batteries re-charging. They are a snug fit so that they do not easily fall off, and they stop the linkage snagging on the inside of the wing covers.
cheers
Tom