On the face of it the contravention occurred.
However, you wish to rely upon an exemption, on this case unloading.
The burden is yours to prove.
Start at the beginning which is you parking, not the PCN.
I am a ******** (whatever your coaching status might be) and on *** I was scheduled to do ***(activity) at ****(location) at ***(time). My equipment comprised *** which I was carrying in the vehicle. I parked in the nearest convenient parking bay and immediately started to unload my equipment. This took *** trips during which I offloaded the equipment, took it to ***, left it secured/delivered it to *** and returned to the vehicle. I would estimate that each trip took no longer than necessary approx. *** minutes. Once I had unloaded the equipment I intended to park my car at ****.
If you could fill in the gaps then we'd have more of a feel for how you might compose your reps.
