Wouter,
The mast builders know exactly light a mast can be built without compromising structure. Be it aluminium or carbon.
(before anyone raises boron composites. A B/C mast would be lighter BUT brittle and very subject to shock loads from a kite).
So knowing that the builders know far better than the lay sailor. Let them decide how to build a mast. By dropping any weight restrictions. We have already height and depth restrictions.

However to make sure no one gets stupid by sailing with the mast de jour (Mast of the day). Put is a rule that each mast, boom, pole and main needs to be registered. A replacement may be substituted as long as the old is deregistered and the registration made in writing and at the discretion of the measurement committee / registerer. (this has worked successfully in the skiffs). Especially with carbon as no two are exactly alike and thus each needs separate tuning!!

This cleans ups the rules and makes it easier to administer.

Im sure the Tiapan skippers will object. However if the skiff experience is a true record. Then the carbon mast and aluminium tip weights issue will be shown to be a red herring.

S..