And getting to case and caseback thinner will be your least problem since DP module and movement and gen dial+hands isn´t exactly common stock and not really cheap and they will be needed to fit in the shaved case and CB.
But if you ever go through with it you probably will have the best rep time and money can get you!
Loosetime actually used a rotary table with his mill to thin out the caseback. This approach makes more sense than using a lathe, since he was able to hold the workpiece in the workpiece holder easier.