You didn't say where you are located or what you expect your winter temps to be, but if similar to where I live, I'm guessing that 50 miles will be right at the limit of your range, depending upon how comfortable you want to be in the car. I'm just going into my first winter with my 2014 i3/Rex. Temps have dropped into the 20's and 30's and I am finding that the 65-70 miles of electric range that I had this summer has dropped to about 50 miles. Full disclaimer: We enjoy our comfort, so we are running the heater at 72-74 degrees and we use the heated seats for the first few minutes to take the chill off of the seats. I'm sure we could extend the range by a few miles by bundling up more and cutting down on the heating, but we (well, mostly my wife) aren't willing to do so.
I would suggest that you see if there is a place at work where you can plug it in during the day. Many employers now days look kindly upon allowing this. If not, use the PlugShare app on your phone to see if there are any charging stations located near your work.
All in all, I am amazed at how much range I am losing in the colder weather, and it's not likely to get any batter around here, as we tend to hit the high teens and low 20's before winter is over. The worst is yet to come...