Hi Rolf,
One of the smartest rules I have ever seen dealing with mast bend and how to make it vary with crew weight was in the International Contender Class. The mast extrusion can be fixed, one design. The location of the hounds can be varied within limits. This way the lighter weight sailors, for example, rigged their masts with a lower hounds position which resulted in a greater bending moment being applied to the mast for a given mainsheet tension. The larger sailors rigged their masts with a higher hounds position which reduces the lever arm to the mast tip. The shorter lever arm reduces the bending moment imposed on the mast for a given mainsheet tension. Since the heavier sailors must control their sails with more mainsheet tension, the higher hounds position keeps the mast from overbending and flattening their sail prematurely.
One might suggest that the heavier weight sailors just start out with a fuller sail and live with more mast bend. This is a compromise because it forces the heavier weight sailors to use a sail that is too full in light winds.
Bob Miller was a smart man.
Bill