Even without GPS, there's the Pan-Am hiway, which runs from Prudhoe Bay, Alaska, all the way to Tierra del Fuego, Argentina, and which everybody in Latin America DOES know leads to the land of WalMart and Taco Bell. Just walk to the Pan-Am hiway, then it's as simple as "Follow the yellow brick road."
Actually it's interrupted by the Darién Gap, one of the more interesting spots in the western hemisphere. Too bad it isn't further north.