Ingo,
I suspect that rear wheel well is an owner modification to perhaps facilitate tire changing at the track...It chops up the smooth blending of the rear 'fender' into the turtle deck. I can't imagine that it rolled out of Stuttgart that way.
One thing's for certain:
That two piece split windshield solves the problem of cracking speedster windshields. Should you replicate it in aluminum, as surely as God made little green apples, someone is going to request that you chop that high windshield by three or four inches!!!
Notice the silver spyder (upper right corner of that photo) with the centerline wheels...and the removable hardtop...very cool!