Unless absolutely everything goes wrong, you'll be 100% fine with 4.5 hours in between EZE and AEP.

I did this same thing (minus the trip to Antarctica -- one day!) two years ago. We had about 4 hours after landing at AEP to get to EZE. You just walk out just past the luggage carousels and there's a booth that sells bus tickets. Hop on the bus, it takes you directly to EZE. Security and bag check at EZE was super fast.

We ended up with like 1.5 hours to kill. I'd keep your trip as-is. Just be speedy once you're on the ground at AEP. It's impossible to miss the booth selling bus tickets, though. It felt like 80% of everyone at AEP actually wanted to be at EZE, so there are a ton of buses making that run.