Latin Americans driving in Japan?

You might be better asking in the "Guatemala" section. International driving permits are good for all countries, not just Japan. Your question is really about Guatemala, not Japan. I think there aren't any Guatemalans on here (except you!)

I get it, there's no Guatemalan affiliate of the FIA? I'm not promising anything here, but a possible fix is a Singapore DL. As I understand it, Singapore will honor the DL of any nation there is, and a non-resident may hold a Singapore DL indefinitely.

Singapore provides this "flag of convenience" DL because...hardly anyone can afford a car in Singapore anyways, so the "paper drivers" will never be on their roads in any case, but they will take their money anyways. So you get a Singaporean DL, then get a IDP on your SGP DL.

If not Singapore, then there may be other likely nations. The point is, get a DL from country that has a FIA affiliate even if it's just a paper chase, then get the IDP on your non-resident license.