I don't believe this is new. One of the Dutch boats at the 2006 Sweden Worlds had banana boards. It was measured and allowed to sail.

The only boats at that worlds that had measurement issues were the ones where the top of the centreboard case was at the extreme beam and the board at an angle. Meant that when the board was raised it was outside the max beam and part of the board was still in the water.

But the banana board boat wasn't any quicker and Ashby won all races (except for last which he didn't sail) on the Flyer 2.