If we are playing Argentina at the Cake Tin I would expect Messi to stay back for the home leg only, if at all. There is very little room for romantic notions in the brutal business that is professional football.
They (Argentina, Chile or Peru are kinda all in the same frame) would simply send a Team B here to get a minor win, even 2-1 will do, or even a draw. I do not think they would see any value in subjecting quality players to rigours of long-distance travel given such ridiculously short turnaround. They would want to ensure the result is beyond any doubt in their home leg. In other words, they would do what we did with the Solomons.
Australia qualified only once when playing South American opponents, and that was achieved by not getting thrashed in Montevideo in 2006 WC qualifiers. They also learned the lessons from the 2002 qualifiers: after the away leg, they flew home direct in a charter Qantas plane with lie-down beds, straight from Estadio Centenario, while the Charruas flew to Sydney economy class with an unscheduled stopover and got to Sydney buggered. Good money put into the playoffs clearly helped. It still took a penalty shootout for the Socceroos to get through.