Doug
There are no open to the public DoC huts in Orongorongos – I think there are two that you can book much in the same way as private huts. Try DoC Catchpool Visitors Centre 564 8551.
Alternatively WTMC has a club hut in the Orongorongos (Paua Hut) which you may be able to use. Let me know if you’re interested and I can put you in touch with the right person.
Andrew