I would go for that. I would think the view out the back window would be better than the Model S sedan.
Though it would have more drag. The more squared off the back end, the more induced drag you get because you get a partial vacuum behind the car that acts as drag. This hasn't been done with a car, but there was an artillery genius named Gerald Bull who discovered a way to increase the range and accuracy of artillery. Artillery shells have a flat back end too and the induced drag was hurting the range and accuracy. However Bull came up with an idea to have artillery shells leak a gas into that void and it improved things dramatically. Today pretty much every country does this with artillery.
With cars, it might be possible to pump used cabin air or take in air from the front and release it into the space behind the car to eliminate the vacuum. That might eliminate the drag induced from squaring off the back.