Stop at Park Headquarters to pick up a backcountry use permit. Fill your water bottles there for the first day as the trailhead has a limited supply. The trip narrative assumes you are staying at the campgrounds each night. There are, however, three cabins in the crater at Kapalaoa, Paliku and Holua. Each has 12 bunks with mattresses, a table and chairs, and a kitchen area with a sink and wood cookstove.
Nearby outside are a water tank and a pit toilet.
The cabins are very comfortable and very popular. If you're interested, write to the above address 90 days in advance of your trip. State your first choice of dates and cabins and then include some alternates. The Park Service conducts a monthly lottery to select the winners. Exit Kahului Airport on Keolani Pl.