If you are just going to be worrying about snow, a limited slip like a trutrac would be awesome. It won't lock up fully but will still apply resistance to the the wheel with less traction, transferring some power. In my experience, limited slips are king in snow. If you also want a front locker for rocks and whatnot for sure go with a good quality selectable locker like ARB.
You can install a locker yourself with a dial indicator to measure backlash, proper tools, and lots of patience.