without trying to sound stupid there are some models of touring caravans that are not designed to be towed by 4x4s, something to do with the boxy designs of some of the 4x4s.
back in the early 90s my dad had a s111 swb and was looking at buying a brand new swift caravan something like a 16 footer and the caravan dealer / owner who my dad had known from when he was in the caravan delivery busness said the model of caravan my dad was looking to buy was not designed to be towed by a 4x4 due to the shape of the car and causing the caravan to sway a lot so in the end my dad bought a cavalier 16 footer.
i know cars, caravans and accesories have all come on a long way since the 90s but its just a thought