Here is an overlayed image. It's a bit small so you might have to zoom in to see it better.
You can use measurements and angles on a piece of cardboard to see what it'll look like in person. You can take that same piece of cardboard to mark out the width profile. You'll still want to round the transition between the sides and top though. I wouldn't recommend going any farther down than the template as you'll see more drag than at template or slightly above, as well as less rear visibility. If you just use a slight curve you could build it a lot more like a conventional topper with a glass back. That will allow you to maintain rear visibility, as well as reduce drag and lift. That report has tons of good info on different mods to pick up trucks.
I hope your stitches go well.