I am wondering about options for a locker or ability to check a bag while out backpacking. The areas we will be are TdP as well as Fitz Roy in Argentina. Would appreciate any recommendations/assistance.

Hi Molly,
I was in both locations last year. In Torres del Paine I believe there is some baggage storage in the park but it is near the campsite or at the hotel, there may also be storage at some of the hostels, as I didn't stay in any I couldn't say. But at any rate it would be charged. What I did and what most people do is to leave any unrequired gear at their lodgings in Punta Arenas. I was able to do this free of charge. I took a very small amount of gear to the park. I would not recommend taking a burner and only bring minimal required food. Food can be purchased in the park and is not as expensive as people often say. Fresh fruit is a good option for the first few days as this is not available in the park. I would recommend spending at least 7 days in the park as trips to Lago Grey, Valle del Frances and Valle del Silencio are essential. People that miss these sections are making a mistake, in particular Lago Grey is often missed because people say seen one glacier seen them all when in fact they differ dramatically and Lago Grey is perhaps the most beautiful. I have heard the circuit is worth the effort but fairly demanding. Extremely winds are the main problem you will encounter in the park. Temperature and rain are over estimated as problems. During the walking season one fleece jacket, a shirt, a rain jacket and rain trousers (I get by with nylon), gloves, hiking pants and a few layers of merino wool thermals will be enough. Most of the time during the day I wore a long sleeve t-shirt only. A good broad brimmed hat, sunscreen, sunglasses, high quality hiking socks and boots are essential. Walking poles are a great investment as well.
The set up at Fitzroy is different, with most people staying in El Chaltern and raditating out on day walks. There may be one or two walks that can be inmproved with an overnight camp. In this sense luggage storage is done through the hostel/hotel. Book well in advance as El Chaltern is heavily booked, and it also has no auto-banking. Again I would recommend at least 7 days. Most people do not stay long enough and regret this, as poor weather can destroy views. I was fortunate to have mostly clear days and walked across Glacier Grande in front of Cerro Torre with a perfectly blue sky. Would recommend the trips to Glacier Vidma and Glacier Grande. The ice climbing is fun as well and not especially dificult.
Good luck,
Shane