On a literary note, my limited knowledge of South American literature means I can think of only one novel about Nazi exiles in South America. And it's not South American but German. Gert Hofmann's wonderful (but unavailable) Before the Rainy Season is about a young German who travels to Bolivia with his fiancée to see his "uncle" on a Hacienda in the rainforest. It also happens to have one of my favourite opening lines:
Come on, I'm waiting for you here on the veranda, calls our uncle, if that is who he really is, for he has long been believed missing in South America.