I want to wire a rear facing dash cam in the trunk of my F60 S ALL4. Do any of you know if there's anything back there that I can easily tap into? Ideally the circuit should only be on when in the ignition state--don't want to rely on a voltage threshold cutoff. Tried the cigarette outlet in the trunk and it stays on when the car is locked so hopefully you guys know of a wire I can tap into back there.