Chopjock,
If its not a black & white, open & shut case, where there is no clear violation of a specific rule, its going to be down to who argues best in court.
I'm with Genghis on this one - sounds like you have a good expert witness if you need one there. If they cannot prove "beyond all reasonable doubt" that you acted in a way that was:
a) reckless, and
b) endangering someone,
they are not going to win. If you can show that you took reasonable sensible precautions, did the calculations, were within the aircraft limitations, ANO etc, how can anyone prove you were reckless? With an expert witness on your side to say you werent endangering anyone either, then at the very least you have created reasonable doubt, even if the CAA disagree.