i have bought a willerby 31x12 2000 static caravan, it is on a slope and the ground cannot be altered, i have tried levelling it , every time i jack up the low side the other side goes with it.
Have you tried jacking up the low side & lowering van on to a concrete slab, see how level that is & then by measuring the thickness of slab you can adjust your level accordingly. Ron.
I'm trying hard to imagine this. It sounds as if you have a three-point contact with the ground when you start jacking, one where your jack is, and the two far corners. This would provide a stable base for the van as you lift one corner, and so the whole end would rise. Jacking both low corners at the same time is probably the only way to overcome that problem.
you need to get the wheels level first,that can only be done by putting blocks/slabs under one of them,this gets the side to side level,then use the jacks to get the back to front level.
You risk twisting the chassis if you try to jack it via the 4 corners without the centre being supported,once level it should also be braced on the chassis rails both sides there are adjustable supports for this although i have seen sections of timber used.