i really want to integrate a 7" into this dash, but im not sure how. The only i can think of is removing the gauges, moving the hvac controls down and putting the screen where the stereo and hvac controls are.
You could get rid of those center vents. I doubt you are going to have anyone in the back complaining about air when they would have no room anyways. I would def suggest getting a spare part to modify, especially on an M roadster. While you are at it, you should route the power for that radar detector, maybe hardwire it with a different kind of disconnect, so the wire doesn't get in the way of your 7 inch.