If you’re considering renting a van and driving around Oahu, DO IT. I rented it for a week and had an amazing experience. The van had everything I needed, including cooking tools, snorkeling gear, and small electric generators to charge my things. It wasn’t hard to find parking, but the best places I stayed at were parks that required permits ($9/night per person) like Malaekahana.
Someone noted that the cleaning fee is high. I would take into consideration the cost of vehicle repairs and maintenance.