Theo:
I use the same setup in a Cap 10. I used a piece of 1/4 in. carbon fibre tube which has a 3/16 hole for the Robart to epoxy into. I also glued balsa blocks into the back of the core where the hinges will go to strengthen it up. I also used 1/64 ply set into the top and bottom T.E. to cover the hinge gap.
Hope this helps.