I didn't realize modifications make it illegal, but I suppose that makes sense.
Still, I may add inserts anyways to make the board better for me. I'm not racing at international events...
Also, I found out about this "adapter plate" that can be implemented without modifying the board. Perhaps that would still be legal - no permanent mod to the hull. I think I could fabriacte one of those pretty easy this offseason. (Add the www to the start of the link below - I guess I haven't posted enough yet to add links)