Is BMW 520d towbar OK AL-KO 3004 stabiliser

Can anyone advise me if the  factory fitted retractable towbar  BMW supply with the current 520d SE Tourer is suitable for use with the AL-KO 3004 Stabiliser/coupling head.fitted to my Coachman caravan. My concern is that there may not be enough clearance between the towball and the rear bumper to allow for the swing of the AL_KO coupling when cornering/reversing. Al-ko's website suggests that 68mm clearance is required between the centre of the towball and the bodywork. Anyone had expeerience of this combination