This might be an excellent time to scout out a local travel agent who has experience in South America travels. I know that everyone here is "internet savvy" blah blah, but there is nothing like the experience of a seasoned professional for what you are seeking. It may not be easy to find, as it is a very specific thing you are looking for, and South America isn't on the radar of a lot of agents, unless it is to put you on a cruise, and get you home.