If you keep your cool when there is a cop on the road you should be fine. But if you seize up and wobble all over the place from the guilt of not obeying the learner laws, you'll draw attention to yourself.
I find that the restriction on night-time riding is stupid, I prefer to practice at night when there are no cars around at all. Was up at 4am last night hooning around Christchurch and it was farking awesome!
And no, I don't show my L-plate because it is ghey. But using it around town would probably be a good idea, for both insurance reasons if you crash, and so you don't get fined.
Chuck it on and forget about it, nobody really cares if you have it on anyway, and in a few months you won't need it anymore. So it's probably not much of a problem.
`Twas brillig, and the slithy toves
Did gyre and gimble in the wabe:
All mimsy were the borogoves,
And the mome raths outgrabe.
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