Just to report that I have driven around the Hainan island during the holiday.
Day 1 – Sanya to Jianfengling Ridge and stayed at a Taohuayuan Hostel
Day 2 – Jianfengling to Haikou and stayed at HNA Grand Hotel
Day 3 – Haikou to Wenchang
Day 4 – Wenchang to Wanning via Qionghai
Day 5 – Wanning to Sanya and stayed at a B&B (without breakfast)
The whole trip, including some branches of the trip, is 1000 km in distance, and took about 500 RMB in gas, and 1000 RMB in car rental.