8K is a joke even with accomodation, it might have been good back in 2009-2010 but today with inflation you will not go far with that amount, especially in very touristy Hainan where people and local shops have for habit for overcharge tourists from the Mainland and even more foreigners.

The days when China was a super cheap country to live in are over, three years ago the government said that all the farmers are now employees of corporations, means they have a base salary in exchange for a fixed amount of a specific foodstuff that they must produce and earn more than they used to do, if they produce more than the required amount they can sell the rest at the market or do whatever else they want with it, means that the price of raw food is rising and thus the final product's price. In 3 years the price per 500gr or pork went from 8 to 15RMB on average in big cities, I let you calculate the insane inflation.

Don't accept anything below 13-14K per month, 11-12K if free (acceptable) accomodation.