I've moved my animals lots of times...on very long cross-country trips, some of them lasting several days or more. It can certainly be done with little risk to your snakes, if you're careful and use a bit of common sense. For me, I've not had to deal with a move with severe cold...but many of mine are in the summer, across the southern US and western deserts...so extreme heat is something I'm very familiar dealing with.
Get a tub just for moving...just about 6" deep and at least long/wide enough to fit your four or five snakes into if they're all coiled up.
Put each snake in it's own snake-bag (an inside-out pillowcase works great for this) and tie each top very securely. A tight knot and then a zip-tie just above or below the knot is not excessive. Also, check all the seams and corners to make sure there's no loose threads they can loosen and make a hole through.
Place the bags all in the same travel tub and fill any excess space with more padding (old towels or whatnot)...put the lid on the tub and secure the lid tightly. Multiple tight bungee cords can work.
Wrap tub in a blanket to help insulate against the cold.
WARM the car ahead of time...then when you're ready to hit the road, move the tub into the warm car. Place the tub in a secure spot within the car so it won't shift or move. Avoid putting it directly over a heating vent, as you don't want it to overheat.
The rest kind of depends on how far and how long you intend to travel. If it's just across town...then you're golden. If it's a cross-country trip, then also consider these things:
Keep all stops as brief as possible so the car doesn't cool off too much. (Or in the summer, keep all stops VERY brief so the car doesn't get hot, which can happen much more quickly) Gas the vehicle as quickly as you can and then get it going again. If you have a driving companion, you can leave the car running while you take turns going to the restroom. I always do drive-thrus during the day (and would do so at night as well, in the winter) rather than stop for a long period for a sit-down meal.
If I have to stay at a hotel, I don't mention the snakes or anything when I check in. I just discreetly carry the box in. Keep the room warm, or set a human heating pad (one that does NOT have an auto-shut-off) under the tub to help keep it warm. The snakes will be fine in their bags for about 24 hours.
Hope that helps some!