When I spoke to Ineos at the drive day about this, they mentioned that they have no objections to one being used.Do Ineos recommend using a weight distribution system in the manual when towing over a certain weight? Some manufacturers do. Jeep recommends one on the Grand Cherokee when towing over 2250kgs which typically produces a 225kgs ball/nose weight (10%). The GC has a 350kg ball weight rating.
However that was about 5 months ago.