Dave,
I plan on doing a glass/ Airex/ glass vacuum bagged sandwich for the skins, just like I did for the rudder. Internal structure will be aircraft grade birch 5-ply.
I plan on building another rudder with lighter glass (3oz vs. 9oz) to confirm the process and check on the weight reduction and stiffness, but after that I should be able to build the inner flaps and then the wings.
Paul