In Hawaii, RVs are called generally referred to as camper vans. Hawaii camper vans are most often class B Sprinter vans or similarly converted passenger vans with sliding side doors.
You’ll find that Hawaii camper vans range widely when it comes to nightly rates. They start at around $100 and go as high as $300, depending on the season, demand, and amenities.
Your permit doesn’t reserve you parking, it just makes it legal for you to park. This is a very real issue campers have to deal with in Hawaii with the high tourist population.