Audi A5 2.0 TDI S-Line Quattro 2010/11

Can someone please help, we're knew to this and have just started looking into getting a caravan.  We've been told by various dealerships that we can tow up to 1600kg but when I use the matching service our car always comes out poorly on the stability side regardless of the weight (unless it's very light).  Can anyone advise on why this is or how we can overcome it without getting a new car. We're looking at 4 berths and most caravans are coming out at around 95-97%.

Thank you in advance for any guidance.