Andy, when you get on site, and on your pitch, check with a spirit level which has TWO levl indicators, one fore and aft, one side to side, placed on the floor just inside the door, and decide which ways need levelling.Some will just need fore and aft levelling, some side to side, and some both!!. Start with side to side and use ramps or blocks and pull the van up on them to get it level, side to side, then check fore and aft, and raise or lower the jockey wheel to get that level, THEN lower the steadies to maintain the van in its now levelled position.