I was wondering, is there anywhere on Oahu you could overnight camp in a small camper van?
Most camping in Hawaii is done on either a state park or a county park. There are no rv parks on any of the islands that I know of but I have just found a place on Oahu that rents camper vans! They will be the ones to ask.
It appears, from my research, that the state does not allow recreational vehicles but the county does allow them at certain parks. I am certain you would still have to get a permit even if you are using a camper, so just inquire when you apply for your permit or check with the county as to which parks allow them.
Upon further research, I found that the county only allows rv or camper camping at four sites – Hau’ula Beach Park , Kea’au Beach Park, Nanakuli, and Waimanalo beach parks – but always double check with the county as things change.
If you need some specific site information see my article about some of the available camping sites on Oahu: Good luck! Let me know how it goes for you.
Big Island Camping – including some links to RV rental sites Hawaii Camping and Cabins Information broken down by island with rules and links