Thanks for the in everyone, I have only driven the car without the caravan connected at the moment, but I am due to tow it down to the west country on Monday. I did have the suspension checked by my main dealer, and they said the original springs were fine, and my R Design model was slightly lower than a standard xc60, mine is a 2016 model.
I must say I was surprised at a 3" lift making my towball 533mm unloaded.
once loaded it should drop a bit, but I am not sure how much.
it is now definitely a lot stiffer now, but I am hoping that when loaded it will not bounce so much on very bumpy roads.
I suppose the keep the stiffer suspension, and get the tow ball back to a slightly lower level, I could always fit a drop plate to drop it down a couple of inches.
I am not sure that a tow ball at 533mm is legal!
any more views would be very much appreciated
Thank You everyone.