I mentioned this a couple of seasons back, but one list of places to keep an eye on are those countries and regions of countries that Anthony Bourdain's Parts Unknown has visited outside the U.S. since its original season premiered in 2013. TAR 28's visit to Cartagena, Columbia is one such place. Another that might be relevant for leg 3 is Salvador, Brazil. it's far enough northeast of Rio and Sao Paolo to have to fly (near the Equator) and the Bourdain episode there relevant several things of interest that could be used for Race tasks in a beautiful tropical setting.
Bourdain has now been to Cuba, Myanmar, (and the Republic of Georgia at almost the same time as TAR 28), so it is something I think is worth considering in trying to pick up where the Racers may be ATM.