Aerynt,
I think the 20 ft boat should be designed for a weight of 160kg (360 lb) and up. This should not prevent lighter sailors from competing without penalty. It is just that the boats optimum all round performance should be more easily extracted from the boat by its intended target market.
I see the target market to be the larger sailors that want to sail a two up boat, both around the bouys and long distance.

Just the way I see it.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!