In grad school I lived with my parents and had a 1.5 hour long commute each way via train, which easily became closer to 2 hours with delays/transfers. I recently finished my CFY and I'm paying back my loans now (agree with you on Sallie Mae!). Yes the commute was rough, but I'm SO grateful I didn't take out an extra 20k or whatever it would have been to live closer.
The summer before grad school started, I made my first semester schedule and I was lucky to have class only 3 days a week. I was originally looking to live in the city as well, but after I was able to schedule only 3 days a week at school, I told myself, "I can commute for my first semester and then see what my schedule looks like in the future." I would talk to your advisor and see what your possible schedule will look like. Also, see what time your classes will be held. Going in 3 days a week from 11-5 is going to be very different than 5 days a week from 8-8. Will you be able to complete your externships near your home? I was able to complete my final externship only 10 minutes away from me.
In terms of social life: I had friends who also commuted and we usually preferred to just get food or drinks after class, which allowed me to still get home at a reasonable hour. Also, you'll probably have breaks in your schedule (class from 10-11, then your next class isn't til 2), and that's another great time to grab lunch with friends or even just hang out and study together.
My best piece of advice would be to take it one semester at a time. See what is reasonable given your first semester schedule and go from there. Good luck!!