Good on you Bug!
Bug,
whether the MK4 ever flies or remains an engineering passion for you, I wish you every success.
The world needs more people like you -- you cheer us all up. Well me, anyway.
And I'd rather be in your machine than in that weird Japanese 4-engines-just above-your-head-thing that we've seen here in previous posts.
Having said that, I think both yours and the Japanese one look great fun -- and there's an American one to check out as well -- the Air Scooter. (I don't know how to add the links).
Happy landings!
Big Ls