I know many here that are on tight budgets and live quite lean (inexpensive housing) and struggle on much more than you are planning.
Groceries / toiletries / OTC meds are pretty expensive in general (easily double and some triple what we paid in the US), so not sure what you will be using or eating for $500 per month. Example: cereal is $16 BZE / $8 US and in the states it would be $4. These things add up quickly! Rice and beans might work out, but TP and shampoo could do you in. LOL
Some of the chinese places have cooked to order meals with lots of fresh veggies. No way could I prepare the dish for what we pay (the chop suey there is $18 BZE and could serve as 2 meals).
You may want to figure in a few other items such as communications (cell phone) or transportation costs (if you buy a bike, have the occasional need for a taxi or need to go to the mainland). Also, the utilities may be different based on where you are - city water vs well or cistern. I think you should allow more for electric (or gas) even if you aren't using AC, you will need to cook, refrigerate, hot water for shower and cleaning and run fans.
In any case, I doubt the local panderers will like you much