Mr: qtla9111, I would suggest a "C" class in the 22 to 28 foot size, some of the units made on the Sprinter chassis are to low to the ground for travelling in unimproved roads should you want to get of the beaten path.
The other point to consider is the availability of parts should anything brake, that is provided that you carry some hard to find items, fuel pump, water pump, a couple of injectors, couple fuel and air filters, belt(s) and then you have the fuel availability, Diesel is some times easier to obtain, regardless of the fuel choice consider installing a Racor water separator and a filter that can be cleaned on the road.
My first choice of vehicle would be a Ford, then Chevrolet, Ford parts and service is easier to find in Latin America.
navegator