Having had a brief look at Wing Ray, I think it would be just as easy to build as a conventional yacht, if not easier. The wing is built up just like an aircraft wing and covered with tissue or solarfilm. No sailmaking, rigging or sail winch to worry about.
If anybody is interested, the plan is still available from Sarik and believe it or not, I happened to see a twin winged yacht being sold on ebay.
If I didn't have a 'want to build' list as long as my arm I might be tempted! It would make a very interesting project. I might still send off for the plan just for the collection.😀
Stay safe all,