In the spirit and experience level of Dave's post, I'll spout off too.
Never tried sanding the belly glass, but I refinished and retilered an old bow to remove limb twist. Dropped from 50# to 44# or so. I had to narrow quite a bit to get the twist out. Started around 1.75 wide and ended maybe 1.6" wide. Starting to get to the point the it looks like a different bow.
But hey man, what the hell, give it a shot.