The Beck Spyder (Porsche 550 replica) is as close to a two passinger Formula V as you can get. I think a tandum with a mid engine would be a little long in the wheelbase. With a rear engine it would be more practical, a lot like a lowered tandum dune buggy, but would not have that mid engine handling.

I've had my Beck for twenty years now. First registerd when I was living in Perrine and working at Homestead AFB. Great car for running the Keys.