I've made a bit of progress on this, not sure if this is useful to anyone because I'm still not there yet, but I'll throw it out anyway.   The potential to edit scale by just messing with the main file is possible by applying transformations to the rest pose. While in blender, click on "pose" then grab either the root (or hips, doesn't matter), scale to your heart's content, then ctrl+A and apply to rest pose. You'll have to do the same exact thing to your mesh afterwards, so push S 1.