You only need a shell when it is raining. Otherwise, you want something that breathes and is very durable. I would look at army fatigues. Look for the nyco, or nylon/cotton ripstop. I would get at least 2 (2 pants and 2 shirts). They will take a beating. You would wear your long johns underneath, if it was that cold. Canvas clothing is also a good option. Look at brands like Carhart, or Dickies.