Yes you could mount it there I mounted my AIT sensor there. Also I have seen Methanol injection nozzles mounted in that spot. best place IMO would be directly in front of the TB which is where mine was mounted on my previous setup.
You're gonna have a hard time finding a nozzle long enough to get into the plenum from the EGR port. That port is deeper than any nozzle that i've seen. The only option would be an annular discharge nozzle and that's gonna be spraying nitrous and fuel in the opposite direction of airflow. Back side of the CAI elbow aimed at the TB is the best place if using a nozzle...... or you can step up to a plate and not worry about that anymore.