Many Latin America airports have independent lounges that are open to J/F travellers (ie SPS.) AA also has lounge-like facilities in LA airports that are not ACs, and would not be mistaken for ACs, but provide some degree of privacy and civilization (ie POP.) Although I have been to SJO I don't know the answer to your question, but a quick review of prioritypass.com indicates they have a lounge affiliation in SJO- so joining them for ~$300 for a year may be a better investment than the F ticket surcharge. Enjoy the pura vida.