What motor is that? Might need to use it as a booster to create a vnCHAD staged Mosquito (vnCHAD - very not cheap and dirty). First Mosquito ever flown into orbit! I'm gonna use mine to peg the ISS!
RockSim is not a good program for estimating the performance of rockets that fly that high.
You need a 6 DOF program such as Splash which calculates downrange distance (X), cross wind distance (Y), altitude (Z), pitch, yaw, and roll. RockSim is a 3 DOF program calculating only X, Z, and pitch.