Sanding the cutaways is always tricky sand paper wrapped around thick dowel or a part of a broomstick is usually the way I do it, sounds like it will be awesome with all your mods. I wouldn't worry too much about the weight though, many builders strive to make their bodies as light as possible. I have some paulownia (Dragon Tree) that I will be making into a guitar, almost feels as light as Balsa wood but is really resonant.