I'd be quite worried if those children were mine, in the past we are supposed to believe not one of them woke up whilst a small van was being broken into and now none of them noticed a van crashing and tipping on one side? Since he's on the wrong side of the road if this were an accident I assume there would have to be loss of control to get there with some erratic movements from skidding and trying to avoid a crash. Then a sudden stop as it hit the pile of snow which would be felt even if everyone was using seat belts, which they are usually not.
No one wants their children to be afraid but having a sense of when something is wrong and being aware of what is happening around them is necessary in life and at least the 3 oldest should realise quite quickly. Then thinking it "funny" that they are stuck in freezing temperatures, with no idea if the van is damaged - the van being their only mode of transport, their current home, and containing all their possessions and food.
Of course if he had told them his plan in the first place and drove it into that position they would not be concerned at all, just another normal day in their family with their dad desperately trying to create something to get the views up.