Here is how the car would look with a boattail that is slightly longer than the length of the nose extension.
This is it lined up with the template
This is with nothing behind it
If I'm going to lengthen the nose I'm also going to lengthen the back like this. I'm not sure as to exactly how long of a boat tail would be reasonable, but this seems like a good start.
Now I'd like to be able to mount this so that the hatch is still useable. I figure that I can create a "platform" by moving the bumper back like shown. I could build it with a frame and then either plastic, sheet metal, fiberglass or something over top. I'm not sure whether to build the sides so that they are part of the hatch or the rest of the vehicle. If they're part of the rest of the vehicle that should make the hatch significantly lighter. I'll try to model what I'm talking about to give a better idea. I'd probably want to move the rear glass to the back of the hatch instead of buying something else clear, and then knock out where the previous back of the car had been. This would add tons of space to the rear for cargo, batteries, or both. I'd have to come up with some sort of rubber gap sealer so that water doesn't get into the car, and to reduce road noise. Does anyone have any idea what I could use?