Plan on checking it at the check-in counter, through to your final destination. Lan goes anywhere from taking a sort-of blind eye, to weighing the carryon. Your EZE/SCL is probably on an A320, which has decent bins, so they might not be as tight. Depending on the airport, and agents, you may not get that thing onboard no matter what. The weight of the bag alone will be near your weight limit for carryon. Just be prepared. I'd suggest an "emergency" carryon in which you can dump stuff into should you have any issues. All this is to say, I've had variable experiences!