Sounds good. Rentals sound like a good deal but was a little hesitant in the past just in case we didn't make it on. Back when AA used to use the 767-300 on JFK-EZE, I remember the heartbreak watching the plane pull back with empty seats in J and Y due to a weight restriction for cargo. I was so sure we'd get on I ended up paying for a 1 night hotel stay since we didn't make it and it was less then 24 hours to cancel. If you haven't been yet, Mendoza and Iguazu are worthwhile side trips. Enjoy your trip!