I did consider changing the towbar from a "flange type" Witter to a detachable one from a different manufacturer), but was told that there was no guarantee that it would raise the height of the ball. In the event, despite having been told from two different companies that there was no adjustment possible,I'm pleased I persisted and obtained the desired outcome.
Our towbar installer put a separate plate between the tow ball and tow bar attached to the car. It,s a oblong plate with holes in each corner. It can lower or raise the tow ball by about 4cm either way.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.