Drop-down stabilisers

I have a 24ft Fulcher van with 150mm G&S chassis with tandem wheels. It has
the usual drop-down stabiliser legs on each corner. My query is how much pressure should I be putting on these stabilisers.

My problem is that when one of my 16-year-old daughters rolls over in one of the front bunks, I get shaken around in my queen bed at the other end of the van. The same applies if someone walks out the doorway using the step. I have tried little or no downward pressure and it's quite bad, and I have tried a fair amount of pressure to the point where you can hear the van creaking from the pressure, and I still get the same result.

Do I just accept that this is the norm and that it will not go away? Are all vans like this? Is there something I'm missing here?

Wayne, Qld