Many countries in Central America have actual Spanish "boot camps" where you as a tourist can enroll and get totally immersed in the language while there in hopes that you will be able to communicate better with the local people. You won't find these camps in Belize. Why? Because the main languages are Creole and English (Creole is a form of English). The absence of Spanish language immersion schools and camps is merely economical. Tourists coming here do not feel the need to learn Spanish so there is no demand for these courses.
However, one can see that there is significant influence by the Spanish language here because many proper names are in Spanish plus there are newspapers and radio stations in Spanish too.
But just because there seems to be no apparent demand for Spanish learning in Belize does not mean that one could not benefit from learning the language while here. Just like many Americans want to migrate to Belize because their dollar will go farther, the rate of immigration of Spanish-speaking people from Mexico and Guatemala is on the rise in Belize too. For many reasons people leave these countries but the main one is to find work. So if you are a North American ex-patriot business person here, you will eventually run into people who will speak Spanish only.
Spanish is spoken here mostly among the Mestizo (mixed) people. At last analysis, there appeared to be a 44% representation of Mestizos in Belize. A second language of Spanish cannot hurt. If you are here for quite some time, you might consider some of the Belize Spanish courses opportunities at the Regional Language Centre of the University of Belize in Belmopan, Cayo District. In this university you can even get certified in Spanish as a Second Language (SSL).
Plus, learning a little Spanish can be helpful if you want to travel to neighboring countries during your stay here in Belize.