[ChopStix]

That's a good cut-line. It preserves the contour right up to the point of separation. The area behind and below the rear fenders needs a box cavity/diffuser.

I'm pretty close to actually buying one of these kits. But I still have not found the right car. Plus I've evolved a bit since we started this topic in that I've grown an appreciation for the 68-71 beetles. Plus most of those have the fold down rear seat option, which would benefit the Delivery body mod.

But I do agree that some aero work (and cooling ducts) are needed under the backend for multiple reasons. I think most of those concerns would actually work themselves out when doing the shell swap. Because you are forced to fill in the open areas as part of the addition. Plus modify the engine cavity as part of the project. So it should become pretty obvious where the problem areas are, as well as where you would need to redirect air, etc.

Also it should be noted that the shell actually covers most of the cars roof. So it will "in some fashion" change the aero of the roof.

I don't know if you've seen the studies I did in 3D and in redwood to find the optimal boat tail shape

Yeah I've seen them. But I have not truly studied them since I don't own a car in which they are applicable - Yet.

Rather than the fiberglass kit, you could graft on some other car's sheet metal. I suggest the roof from a 1948 Studebaker Starlight coupe with a V-cut down the center top to fit it to the Beetle's width. Or replace the rear quarter windows with the halves of a split back window.

There's almost zero chance that I would chop up another car to make a wagon/suv. Well unless I found a donor that was roached out that happened to be really close to the receiving vehicle in proportions. Even then I try to not take on crazy fabrication jobs. But I say that with an asterisk.

The reverse curve adds 4ft. A regular 45 boat tail adds 3ft. A 'phantom tail' truncation at the stock length would be at that box former

I appreciate the "aero work" you Eco forum guys have done on various vehicles. But I seriously doubt that I would ever make a full on boat tail on a vehicle. I know and understand the benefits and all that. But there's a conservative limit to my custom car desires.

The tail lights in that instruction manual picture reminds me. I don't have a picture, but the tail lights on the car in my avatar were swapped side-to-side and mounted at a shallow V angle, like an old Valiant.

I'm not sure I understand what this looked like, and more importantly why you did it?

Or I could forget the beetle and just buy one of these!