RE: Demoiselle Plans?
Lee,
I can't speak for the original Demoiselle but I believe that the "improved" version that was constructed for the movie had the pilot sitting a little farther forward, perhaps forward of the CG. It looks like your pilot is sitting closer to the trailing edge. Santos Dumont was a short-statured man and he still had to hunch over to fit under the wing because the Demoiselle was a tiny airplane. What this means is that the pilot was a larger percentage of the flying gross weight and, thus, his position about the CG was more critical (much like one of the modern ultralights.) Moving him just a few inches forward might have completely cancelled the lack of any fuselage weight forward of the CG. There's also a chance that the movie version was constructed with a shortened tail.
While this may not help your model balance any better, it would explain how the movie plane was able to fly better than the original (which was supposedly "squirelly").
Harvey