Your thinking is sensible in your suggestions. However very lenient. 20 Kmh over the speed limit is excessive and reckless. What is the leniency that the NZ police allow? You will need to be clear that overtaking is not an excuse to speed, and road works are not. If this is not clear you will have endless excuses and will not move forward.The law is the law, and overspeed is overspeed. Good luck!