There was a guy down in the west country that had one about 15 years ago, not heard any more of it since, it might have gone to europe.
Keep on the lookout for 5.5 hulls and a inter20 mast, then make your own. Talk nicely to the NacraUK guys and see what they can do. There was one put together recently for a US customer - gonna cost a few quid tho!