I think something else you need to ask yourself is are you using poly as a way to play the field before you decide on whether or not you want to dump your existing boyfriend.
I was pretty much in the same situation as you in college, only my boyfriend was 45-minute subway ride away and the guy I became interested in worked at the same place where I worked 12 hours a day.
Did I want to break up with the boyfriend for the other guy? Not really. But I wasn't ready to get married to the boyfriend. It ended quite poorly.