So how many inches of boat-tail are you planning? Sven7 is at 41"; I'm planning on 36". Even 18" will give a benefit.
Instead of a mirror delete; how about two mirrors farther forward.
This moves the mirror out of the airflow around the A-pillar. Have you seen the pictures of people running 5 mirrors in the interior. I've only got one, but it's 2 1/2' wide. An example:
http://ecomodder.com/...#post208199