travel around South America

I’ve always wanted to travel South America… leaving from Dallas, heading south until I reached Chiapas, then continuing along the western coast until I reach the southern tip of Argentina, then back up around the easten coast until finally I travel by boat from the northern coast through the gulf of mexico to La Habana (or atleast Cuba, where I could hopefully make my way to La Habana). Returning through Mexico as I left. Method of transportation is completely irrelevant, and it seems as if it might be a bit dangerous. Visas and proper paperwork also seem like they would be difficult to organise… at any rate. This is something I will definitely do before I die.