I have been exactly the same way. Whitebaiting is always something I have wanted to try. Something about the river bank, the stealth, the lack of movement (ie you have your spot and don't move far from it) and the general totally Kiwi side of it. It looks like relaxation plus!
I have a mate whose family is from the Coro. We were given about 2kg's of 'out of the water that day' whitebait a few years ago. Amazing times using whitebait for every meal like it was like any food. The bonus is, that my mates dad is happy to take me baiting. Just need to find the time (that works for us both).
Why do I say this?
1) because there is Whitebait on the Coro but you really need to know where to go. And whitebaiters are even more previous than fisherman about prime spots. You could at least try there (with the right research of course) and come up trumps. The Coro could be worth a shot.
2( The Naki is very popular for it. This place here I have been meaning to rent for some time. Mokau is meant to be the whitebait mecca of the North Island. If you are prepared to drive and rent a house for $85/night, I know you can rent spots to try it from. In fact, I am sure this bach did theirs in the past.
It definitely is something I want to pursue.
Finally, an e-mail regarding the Coro from my mate this week. may be worth keeping in mind.
"Whitebaiting, is currently off the agenda as dad is working on a fishing boat and he's out for a few weeks. He said last week that there are a few enunga's amongst them so the best is past. I can aks him after he's back in though.
Yeah once the enunga's start appearing then the best of the season is done. Just re-read an email dad sent and he said now that he is out fishing his whitebaiting season is over. There might still be more coming in but I'll have to ask once he's back.
Good luck!