From the top down, in an ideal world, you would superimpose 2 template like this.
But who are we kidding? Trying to design this into your shell would be very complicated, and I don't believe the return would be significant. I have thought through your design and this is why I say V2 is great, you don't really need to worry about the sides if you don't angle down the top too quickly. If you put the tail cone on, this would need a bit of a side taper. The thing you're trying to avoid is a pair of huge tornados that you drag along behind you everywhere you go. This is caused when the top drops too quickly, and the sides don't. The lower pressure created on top drags up air from the sides and makes a mess of things.
Look at this link to get a better idea of what I mean.
Page with lots of Vortex Talk
So, if you build your new shell based on the side view in post #22, just be sure you come in gradually and only about 10-12 inches on your tail cone area from where it attaches to the straight sides and I think you'll optimize your space, and avoid the dreaded big butt vortices that really kill you.
The reason a vortex is bad has to do with the energy it takes to maintain it. Keep in mind, the air you're driving through is standing still. We have it in our minds so strong that the air is "Blowing" over our vehicles, and for a lot of things, this is OK to think this way. But when considering the Vortex, it helps to keep reality in mind. The vehicle is pushing through air that is not moving. (Assuming a calm day)
Now when we minimize the amount we disturb, or set into motion, this still air, then we end up imparting less energy to make it go in motion. When you create a tornado that you are dragging along, it requires a large amount of energy to keep it moving. Remember the air was still before you came along, so if it's rotating after you left the spot, that requires energy, the bigger the vortex, the more energy required.
The key is to minimize the pressure differences that are close together, so by modestly tapering your top, you don’t create as much low pressure that is going to try and suck in the higher pressure air from the side. At the back tail cone area, where the top starts to angle down more, you need to taper in the sides to form a lower pressure there thus keeping the air from moving up.
I hope I didn’t lose you there. If so speak up and I’ll try drawing something or figure out another way to put it.
You may want to reconsider the whole foldable tailcone thing and make that interior space instead, as long as you don't pile a ton of stuff in the back, I'd think that room would be gold to you. Heck, that would be a good place for the bed to go and really stretch out. just sayin.
Also, I notice you're pretty aggressive on the bottom coming up, this should be 10° max and I measured it to be a bit over this at 12°. You may want to rise more gradually there.
Hope this helps.