I used RocSim 7.04 to finalize the layout and weighting of the rocket.
I planned on using a Cessironi PRO 38 J285 for my certification flight. RocSim showed that I would need 8 oz. of weight in the nose to keep the rocket stable. (See the construction page for how it was attached.)
Here is the file: phantom-4038.rkt. Right click on the link to save locally.