Things I carry for ordinary winter travel locally include sleeping bag, a pair of bunny boots, a set of Carhatt arctic coveralls, arctic mittens, a bunch of hand warmer packets, fleece face mask, my usual beaver hat, snow shovel, jumper cables, tow rope/chain, things to start a fire. When I'm going long distance I add extra stuff like a portable Coleman stove and heater, chains, extra vehicle fluids, a bit of food, etc. Multiply some of that stuff by 5 to account for the wife and 3 kids. There might just be enough room for them after all that. My wife thinks I overpack sometimes, but I'd rather be safe than sorry. Before last hunting season I picked up a portable aviation VHF radio that might be handy to have in the car/truck if you get out of cell coverage. I've also started looking at satellite phones since I've started to take my young sons to remote hunting sites with me. That would apear to be the ultimate emergency communication tool to have if you got stranded anywhere, road system included.