Hi,
We have had a few ski holidays in our van. Many good suggestions already.
Do practice putting chains on, I've only had to do it once, at night, blizzard conditions, needed a shovel to clear round the tyres, head torch to see and full set of over gear to stay warm, it's not a nice experience.
Take a good collapsible shovel, ski touring ones are best.
Sound like you are sleeping in the van, if you are using the pop top up be vary careful of snow in the roof mechanism and around the roof, especially for lowering, awning side collects most snow, we have a topper that is very useful for keeping the bulk of the snow off. Topper is also very useful to help the bed area stay warmer. Telescopic ladders are great for getting up high to check and remove snow.
Extending scraper / brush essential.
We have used campsites with drying rooms and boot warmer storage, bliss.
Assuming you are on hook up take a small electric heater, we have a ceramic cube one, you can leave that on low all day while you are out the van, nice to come back to a warm van.
Van drinking water can freeze, take container to fill and keep in the van.
Old rubber car mat is useful for outside the sliding door.
External front / side screens are best, you will get a lot of condensation with internal ones.
Have a great trip, bon ski