Hey, I'm glad that bow came out that well. Great job working through and fixing up the tiller.
If you have a decent limb width, you certainly can temper the belly, and probably can pike it, too. Be conservative. Half inch at a time or so.......
Who says that you have to sand it? On more primitive looking bows, lumpy staves,
.etc. I often knock down the tool marks with 80 grit, move right to 150 grit, and call it good.