I have a 2020 yukon XL and when pulling an 18ft boat at 50mph I will get a bouncing of the car. It only happens on certain parts of the road but in order to stop the bouncing I have to slow down and then it will start again down the road. I have had the trailer tires road balanced and no change. The car only does this when trailering and not at other speeds. I can pull the trailer at 70 mph and it runs smooth as can be. I wounder if the MAGNETIC RIDE CONTROL can be causing the problem as once it starts it is like the trailer oscillates and keeps the bouncing going until I either slow down or go faster. I am open to any suggestions.