VW is a big brand in Latin America. That being said there are differences in vehicle standards by country, meaning they aren't necessarily the same (parts might not be easily interchangeable). Lots of VWs are used to traverse the Americas and VW mechanics can be found, some are European ex-pats. Now, if you break down in a country that has an import restriction on used parts it can be tricky to get what you need. Again, people have done it so it wouldn't be the end of the world just an exercise in problem solving, patience, and bureaucracy. We personally came across travelers in Westys, Kombis, and Syrcros along with all of the newer models too. There was a mix of home build and professional builds. I'm not sure how far away from your trip you are but a couple great books from those that drove the Americas (and more) in VWs are:
Wide-eyed Wanderers | A Befuddling Journey from the Rat Race to the Roads of Latin America and Africa
Drive Nacho Drive | A Journey from the American Dream to the End of the World
A great blog by a couple of professional journalists,
Seventeen by Six, covers their Pan-Am trip (2011-16) including an epic 11 month breakdown. Don't let that scare you, they decided to switch their Eurovan from an automatic to a manual transmission which greatly compounded their problem.