Just keep liquids at the limits, in sealed bag. But to Calafate make sure whatever you plan to take as carrying really is under the weight limit, or they will make you check it. Also people go kind of mad trying not to check things, so try to get in the line for boarding quickly.
Re the 4 mos baby, if you have a lightweight stroller I'd bring that just so you have somewhere for baby to sleep when out eating. Bring your baby bjorn style carrier, and if you're renting a car bring the huevito, but otherwise you might find it a pain. Ah 4 mos, they weigh so little, it's relatively easy, and they don't take up much room in the bed, most can't even move yet so no kicking etc. (we have a 20mos, almost 13 kg -- we've just moved house and he hasn't taken it well, has ended up in our bed most nights, which mean husband and I get about 15cm of bed while he stretches out like the bar of an H in between us and pushes and kicks until he is satisfied that he is occupying as much space as possible!)
And a quick Aerolineas story -- Thurs husband flies to Mendoza for day -- flight out 615am, back at 7 pm. Flight out delayed almost 2 hrs because some crazy guy, who got past security some how, ran past the attendants at the gate and onto the plane and it took security ages to convince him to come off... Eventually he did in handcuffs and all. And then on the way back there were two security guards traveling in the plane. As the plane backs from the gate and starts taxiing to the runway, one of them asks the attendant "this is the plane to cordoba isn't it?", "no that would be the other one beside us" They actually turned the plane around and unloaded them... And then the woman says oh but I have a bag.... There was another hour delay while they waited for luggage services to come and dig her bag out of the belly of the plane. Unbelievable.
