Hello,
As someone who is also considering going to Salem State in the fall, I recommend living as close to Salem as possible. I live in the Boston area, a little south of it, and I was looking into the commuter rail situation and it looked like a 2 hour commute for me. Living in or around Salem sounds like your best bet, but definitely look for something that is on a bus line going into Salem. I will remain where I am living, so if I decide to go to Salem, I will be getting there by car.
Good luck!