I was not going to make this but decided to try it. The only spy photo is a video from CZ here on YouTube. It does look like the rear side window is larger and without the secondary pillar. I have no idea if this will be the shape of the roof but I tried to make it close to what can be seen in the video.
Update: with more spy photos appearing, I updated part of the rear side window to include the small pillar which was not visible in the video.