Rather, go to Atacama, in Chile. It's a desert with pretty transparent air and little to no clouds, far from anywhere, and easier to traverse than a forest.
It's also rather closer to the South pole, so not as hot as Amazon.
Apparently the desert in Kashmir (I think Ladakh specifically) is also excellent for astronomy for similar reasons - a dry desert, cool due to its altitude, and also benefits from thinner air causing lesser distortion.
