This is the rotisserie in its finished state

As you can see the post slides up and down and is secured by the 2 bolts fitted. I havent had any problem with this set up. It was easy to load the car on to the rig and with the assistance of a trolley jack it was easy to raise up to the working position. The only thing I would possibly change is to put a bolt through the inner posts so that it could "pivot" slightly as the front jockey wheel can lift off the floor when rotating the car.