I stayed at Wai'napapa, near Hana on Maui, not far from the 7 pools
Had decent little cabins when I was there, kitchenette and all. Last trip got the reservations and we got cancelled due to Dengue Fever(no, seriously, Dengue Fever)So you may want to get a back up
Hawaii State Parks
they have camping at a few of them, depends on how rustic you want to get