What do you plan on boating?
I was there for last Dec-Jan, and I boated a lot. What sort of stuff were you looking to hit? Heli-shuttle V trips? Then I don't know, except go to Hokitika. Less then that? Go to Murchison and find some pals at the campground. Also, buy the guide book, but be warned, if it says "hair raising" they really mean it. I was on a IV on the hollyford, and halfway down, around a corner, with no sneak, was a nasty V. My buddy and me both agreed it was really f*cking ugly. We walked it, but be careful. Go look at Huka falls, on the north island, and tell me if it looks like a IV to you! It does to them, but Kiwis are pretty demented.