Not sure if this makes a difference but my destinations (in no particular order although ideally): YYZ > Montevideo, Buenos Aires (although I realize that from Montevideo to Buenos Aires I'll have to pay my own way) > Mendoza > Santiago > YYZ.

Come to think of it, Montevideo to Santiago I'd be paying on my own...
Maybe possible to add on a trip to Mexico City after Santiago perhaps, but likely wishful thinking...

Thanks again!