There are very few RVs in Hawaii. Most of the reasons are entirely practical: You can't really travel via the interstate, and you'd be limited to one island at a time. RVs are expensive to transport from outside the islands, and they often require a special license because of their size. Then there's parking. There are few places in Hawaii to actually park an RV.
There are no private RV or mobile home parks or other specialized facilities in Hawaii with water, power and sewer hookups for RVs. More importantly, state and county agencies do not permit use of RVs in public parks or lands. Even tent camping is strictly regulated.
So why do we even have a button for Hawaii in the state navigation? Because some people actually want to know about this!