I would think your bags will be checked through w/no problem. I don't know if your BPs will print that early, but probably they will. You'll have to pay a departure fee @ EZE and an entry fee to Chile. Make sure you arrive SCL for possibly lengthy exit migration lines for flights at that time. If you are in the front cabin, there is a premium check-in room @SCL should you need any special services at the far left end of the main terminal building. If for any reason your bags are checked through only to SCL and you want to enter Chile, I'd just go through customs, get my bags, and go up to the premium check-in area back upstairs, where I'm sure they'll take care of you.