Interesting setup. Good to know. I do have a car seat back there so I am not too concerned about things sticking out of the rear seats provided they don't impair the car seat attachment points.
Current: 2009 E90 M3 | SG | FR | 6Speed | Akrapovic Evo | JRZ RSONE | StopTech Trophy | Cantrell Brake Ducts
On order: 2016 F80 M3 SO | AB XT1 | ZCP | etc.