Is moving payload masses during flight to restore mass centering, or to avoid having to trim, a useful approach?
While I don't know of any airplanes that move load in flight for CG purposes, there are definitely airplanes that have various fuel tanks that can be used to trim the airplane during flight. Some of these systems will move the CG aft after takeoff for better performance in cruise, and then move the CG forward before landing for a more stable approach and landing.