This is really fine Kiwi style butt-boating: camp in the huts walk up the trails and packraft down.
D’Urville River is Class II, one spot Class III, but there’s a big tunnel going through solid rock that you have to portage. People have hiked into it over passes to the south and rafted w/packs in classic travel style. It’s pretty fun and relaxing
Sabine River is best packrafting I have done yet in NZ out of, say, 15 runs. For you Alaskans picture Echo Bend meets Little Su with drops as tall as Ship Creek. It’s about 9 miles long with a portage at the bottom of a big Class V gorge – of course on a trail. It’s got a bunch of Class III with one 5-drop Class IV and then all the Class II boogey water. Beautiful color, lots boulder-scoutable drops, and beautiful valley of beech trees with snowy peaks in back. Highlight of the trip so far.
Get to it and the D’urville by taking the Lake Rotoroa water taxi (NZ $40) and 4 days or so of food. Buy a hut pass and stay at the Sabine Hut. Do each river as an up and down day trip. The Sabine is really, really good.