I actually made an outback map, basically a reskin of the Great plains map, with Sertanejo (to represent the first struggling settlements out there) and Afghan Cameleers. Most of my map making skills are gleaned from copy-pasting code and a smattering of XML knowledge from the days of Civilization 4, so I haven't been able to change its name. I think its uploaded on the AoE3 Heaven blacksmith, if you want to check it out (I have no idea if it works with the latest version though).
Also, I made the Llanos map generate natives besides the Cherokee and Cree. Its basically generates all new South American natives because I wanted to see what they were like, but could you tell me what the map's natives are supposed to be?