Goddardca,
The blue one you took the bump and window off of was what I was thinking... After seeing it that way though, I agree with you, not feeling that so much - makes the back end look weird. I wonder if they'd keep it a 4 seater for the convertible, because that hump in the back might be odd if it's right next to the rear passenger's head!
The way you have it picks up the shut line of the doors nicely, so that seems like the most artful way of doing it so far. keep up the good work.