A question often ask and much disregarded
although the tow bar weight is within limits
the load distribution bars ( torque bars -stabilizer bars --sway bars etc) not only help distribute the load but act in such a way as to stop the trailer /caravan for developing the sway that tends to make the driver loose control at speed
they also , when properly adjusted, keep the ride height of the towing vehicle level and that improves stability
remember that although the bar weight is 175 kgs that amounts to a load of 525kgs over the rear axle or extra 525 kgs on the rear tires ( mass multiplied by distance from drive axle or rear wheels assuming the distance from the axle/tires to the tow ball is i meter---heavier if the bar is further back from the tires )
to use the distribution bars lifts that weight off the rear axle and places more of the load on the trailer wheels
As a result the car / trailer combination is much safer to operate than without the bars