I've never read anything that focused on the tropics, since I am a temperate zoned person, but the principles are going to be the same. Have you read anything on regenerative agriculture? In my part of the world, getting water to soak in tends to be the first priority. If you're on a mountain, keeping soil from washing down the hill is probably the top priority? Could terracing work? Are they eating native foods? I'd be thinking on how to make agriculture work with their free range animals because changing that is likely to be too hard and it might well be helping limit the amount of disease. It might seem stupid in such an impoverished context, but you'd have to have a thorough understanding of the *advantages* to whatever they do, before you could move forward. Change is effort and these are people who are already using what effort they have, so to make changes, whatever you do will have to feel like less effort and not eliminate the advantages they already have. Better the devil you know, and all that.
Huh. When you're done, you can write a book on trauma-informed agriculture. That'd be interesting.