What happend if you put wlan0 into monitor mode using
ifconfig wlan0 down
iwconfig wlan0 mode monitor
ifconfig wlan0 up

I assume you won't get that macadress problem.

Note: This worked on N900 before airmon-ng was fixed.(the mon0 couldn't monitor other channels if wlan0 was connected to an AP with that particular channel.
Note2: I don't own a N9, but I thought my experience with the n900 might do this awesome project some justice. Good luck!