Welcome to the old car club. I'm originally from South NJ and this ol girl lived most of its life near the beach and I drove it daily for years through some of those storms. So here are my suggestions for running in the winter, wash it every week, you want to wash all the salt off often. Spray under the car and every spot and wax it often. Salt is what causes the rust and will eat even the best wax jobs fast. If it was a good full spray paint job you should be fine, but make sure you take precautions because someone stealing it and wrecking into you would be my biggest concern. I run 3 kill switches, a easy to find ignition, a harder to find distributer cut off switch so the motor will turn over but not start, and finally one that goes to the fuel pump so if they even start the car, they won't drive far. Of course that doesn't stop your crooked tow truck driver/flat bed driver, so make sure you have good insurance
Theres nothing wrong with driving a old car everyday, I did it for years. Matter infact I was trying to get a trade going for my 03 CVPI for a guys 65 Oldsmobile Cutlass 4 door so I could have it as a daily driver thats a little more interesting that my CVPI, plus maintiance would be cheaper and easier
BTW what motor, transmission, and rear gear does that mustang have?