I'm gonna throw in a couple "must haves" based on my time off roading.
At a minimum I'm going to have a handheld radio for the times I get out of the truck. I also make sure my co-driver/wife has one. There have been times I needed something and I was not near the truck, so I asked her to grab it, or I would have if she had a radio!
I also would say invest in a REALLY good headlamp. Flashlight are great, I love them, you love them, we all love them, but when you're doing something with both hands, a hands free light is the cat's me-wow! I have a HC90 from Nitecore and love it. It's bright as the sun, totally adjustable from 0-900 lumens, lasts forever on a rechargeable 18650 battery, and you can charge the battery right through the head lamp. Not cheap, but I use it the most of all my lights.
I got a kinetic energy rope from Billet 4x4. I love it because it's blaze orange. Whoever thought WHITE was the right choice for a rope that will be used in the snow (and in the dark) should be flogged. I heard Southeast overland changed their color to black, so good move.
Oh and for that radio, I'm going to get a chest harness so I always have it with me, only need to turn it on. I've done a lot of chainsawing during the snowballs, and having the radio in my face while my Stihl is running means I'll hear the cries that somebody is stuck (in Delta) again.
Todd