Using Levelling blocks

After unhitching the van on a pitch I realised I needed to use a levelling block. I tried to do this with the motor mover but found it difficult because the block in front of only one wheel made the van start to turn when it moved forward.I managed by moving it slowly and pushing on the front corner of the van to keep it straight. Then I had a lie down! I understand why this occurs but wondered if there was a trick to this or if I should have just hitched up again?