Since I know that OpenRocket does not know how to deal with Tube Fins (Yet), and this rocket has two of them (The rings), it will give a result a bit lower than expected for stability. That said, since it does not appear that adding .5 oz of nose weight will really hurt anything I may go ahead and do that. As you said, it was already a marginally stable design, and will depend somewhat on how well the rocket is built (i.e. any extra weight added to the tail).

Also, it's nice to have a good output from Open Rocket / RockSim with you just in case the RSO has any questions on the rocket.

__________________
Member: Washington Aerospace Club NAR Section #578
NAR #94383
TRA #15009
HPR Level 2