Admittedly I have not read the entire report. However, do you have a picture of the rest of the parts recovered? I have a hard time believing that a Performance clam shell cone could go sideways at mach 2.65 and remain intact, while damaging the glassed phenolic. In my opinion, the 54mm tube is more robust that the cone you were using.
I just don't know how much is left of this rocket to assess the damage. There of course is a likelihood that the booster tube failed, seeing as that has yet to be recovered.
Additionally, to minimize weight addition, I would be sure to double wall any tubing that is spanning open air within the rocket. For example: from the top of the motor casing to the altimeter bay is a single thickness of tube. Epoxy in a coupler to double wall that area and that should strengthen it significantly.
TRA 10904 L3
2013 Flights: 8
2013 Ns: 7,609