Mike
The interpretation of the CP/CG stability relationship is more involved than simple RockSim static stability analysis would lead you to believe. Your trying to solve a problem that doesn't exist.
Your rocket with 3 calibers of stability is not over-stable.
The late Bob Dahlquist wrote an excellent experimental wind tunnel paper on Wind Caused Instability in the the March 1998 issue of High Power Rocketry but it's too long to post here, and not currently on the web.
Robert Galejs's followup article on "Wind Instability - What Barrowman Left Out" in Sport Rcoketry explained some of the phenomenon that Bob observed in the wind tunnel. It's an excellent review of what really determines rocket stability.
https://www.cmass.org/member/Robert.Galejs/sentinel39-galejs.pdf
Your Sudden Rush is a "long/skinny rocket" with an aspect ratio of 22:1. It you read Robert's article, you will see that the "over stability" goes away in a cross wind because the CP moves forward on long rockets because the simple CP calculation do not properly account for the lift of the body tube for non-zero angles of attack, so you don't have the stability margins you think you have based on the simple static calculations of RockSim.
It's always a bad thing to add extra tail weight to the rocket. All it does is reduce the rocket's stability and make the rocket
more likely to weather cock in crosswinds.
The real source of the "instability" problem in crosswinds is being underpowered when leaving the launch rod such that the angle of attack of the rocket is large and the rocket is near the aerodynamic stall point. The cure is a longer launch rod and/or a higher thrust to weight ratio motor to obtain a higher velocity before free flight. You shouldn't fly a long/skinny rocket from a short rod or on a motor much under a 10:1 thrust/weight ratio on a windy day if you are concerned about stability.
Bob Krech
