ORIGINAL: Tarasdad
What I ended up doing is using a razor plane to shave away the bulk of the material. Final shaping and alignment are being done with a tool provided in the kit (Carl Goldberg Tiger 60) that holds a piece of sandpaper at a 45* angle. Once the control surfaces are attached all gaps will be sealed.
Whatever works for you, go with it!
In time, you'll be doing a lot of edges and mastering the art of shaping.