If you want to have it level wind the jockey up half way put a jack stand under the draw bar, on blocks if need be, then reposition the jockey wheel with some blocks under it and wind up again till you get the level, hold van with jockey and repack the blocks under the stand, don't use the jockey wheel to hold it up a stand for parking up is way better and safer and don't extend the stands post too much, better to put more blocks under it for stability, of course wheels should be chocked front and back, many don't realise that the van can walk back on a slope as you play with levels. You may have to step the blocks so the jack stand is level.
If you have a tandem axle its best to try to keep the wheel hubs on the same plane, front wheel hub is close to the same line as the rear one this will allow the weight to be evenly spread over the axle set up, raise the front or rear too high and the axle can actually be hanging from the chassis with the other axle taking all the load... so you may need to run an axle up on a ramp or block, so run van back further than you want, place ramp and roll downhill on to it till you have level or near level axles........ I used to just run my front axle onto a 40mm block at daughters as I had the front up about 1.5 jockey wheels , of course the jack stand was sitting on a pile of timber about 300mm high, I hated it.
Never use the stabs for any lifting, they just stop the rock when the wind blows, or other things.... If you need to use the stands and its too high just pack up with some blocks/rock/brick etc just dont load them up.