Thanks for the kind wishes, everyone. I did get on a flight today, no thanks to GOL. After dealing with GOL all morning and getting nowhere, I finally called AA's Sao Paulo office in a state of panic but the agent that answered the phone and her supervisor were able to get me on a flight tonight.
Apparently this happens at 2-3 times a week with GOL, so the Brazilian office is very familiar with the issue and is taking steps to address it with GOL before their partnership can expand. GOL Agents do not have access to TIMATIC, when they check in an international passenger they have to call some sort of documentation center that is staffed by a third party to find out what is needed and this center frequently gives bad info.
Even today, it took 45 minutes to check in between calling the documentation center and having to manually type in the APIS info as SLZ does not have passport readers at he check in counters.
Lesson learned.