mrsbondee, I am also a nurse, and have researched this before. The average salary for a nurse, RN that is, is about $12K a year, Belize money. That is $6K US. You can work as a nurse, but have to get all of the typical paperwork/permits in order. I agree with Alan, it may be better to volunteer your services with a mission type organization, based in the US if you want to use it as a tax write off. I did a medical mission, and had a "license" that was valid for one year, but have not tried to renew it.
I would be interested in learning what you find out, if the regulations have changed any in the past five years. Good luck, and please let me know what you find out.