RE: Sig Hog Bipe Build
As best I can remember, you should be able to build wings first. We were very careful to construct a flat building board and make sure that the wing was fully pinned down, especially in the step that "sets" the shape of the wing. Both wings came out perfectly true.
Found it best to wet sheeting on wing D-tube and turtle deck so as to bend without cracking. Just wet with rag and let sit a few minutes.
Haven't flown it yet. Waiting for a break in the weather.
Good luck.