I was perusing the world wide web in search of figures for South America or the Caribbean during the Banana Wars period, and came across a mention on a gaming site about perhaps using Chaco War figures for opponents for U.S. Marines during the 1920s and 1930s. That is one Gran Chaco of an idea! (pun intended)
|Paraguayan infantry - Pic from Khurasan website|
For rules I do have a couple of options. I did work on rating the two Chaco War combatants using Force on Force (see this post), and years ago I put a bit of polish on Greg Blake's Yanks Up the Yangtze which was written to cover the gunboat period in China (and you can find a link to the latter rules at the top of the right column on this blog). I am fairly certain that YUTY has rules to cover gunboats and moving the setting to South America should be fairly easy.