I have not yet trimmed the plugs flush, but I will and then fit a 1/8th hard balsa cap over the trailing edge. This is not really as thick a cap as I would like, but again I am trying to work within the confines of the precut gap. Glue the cap on with white glue (I use Pica Gluit exclusively, it sands very easily). Again, the elevon is not shown here but is capped in an identical manner. It does not matter how wide the cap is as we plane the excess off later.