Bill,
Good, glad we saw the same light.

As for me, I would coat it with film. IMHO a huge weight savings there. Another idea, since you are now lightening the model you can probably go with 5/32 wire on the lg mains instead of the 3/16 I provide in the kit. Let me know if you want them, I'll bend a set for you. BTW: the prototypes Duane, Kevin and I built have 5/32 wire.

As you mentioned, you can the cut the centers out of the outboard ribs. Obviously, there is less stress and moment on the wing the farther out from the cg. So, yes you could remove more weight in the last 4-5 ribs/cells. Removing more and more as you near the tip, like no shear webs in the last two ribs/cells. Make sure the wing tip is very light (or eliminated altogether) so as not to stress the last few ribs/cells (if you significantly lighten them).

Could probably actually lighten the 3/4 x 3/4 leading and top edge of the fin. Cut lightening holes in with a good scroll saw. There may be other opportunities in the fin, too.

Duane has already mentioned how Ed hand picked every single sheet and stick of wood in his kits, he had to, he was in national competition. Of course, as a "kitter" I don't have that luxury without significantly increasing the cost. It will be interesting to see what you come up with Bill. Write or call me if you need help in getting to that point.