VW Tiguan Height

Hi All, I have just a tow bar fitted to my tiguan, and I am concerned about  the height. It  is 470mm to centre of unladen, I think this is  too high, but  both witter and the company who fitted it say this is ok.I know the car is new therefore suspension is a bit stiff,but cannot see it dropping 50mm to the recognised  height of 420mm when car is loaded and caravan hitched. Havnt had chance to test it as quite a performance to get van out, but going away at end of month. I understand drop plates are illegal.Has anyone else got a tiggy with tow bar fitted.