It is the nature of the beast. Strong-arm or Bal locking stabilizer bars on the front landing gear will help a lot. There is also suspension bounce that nothing will take care of as the frame will flex in the center of longer trailers. When set up for extended periods I slightly jack up (enough to stabilize) the leaf Springs using a bottle jack under the leaf spring equalizers. Scissor jacks at the Centerpoint will provide the same support.
Remember, it is a camper on a frame with suspension meant to go down the road. There will be some bouncing, shimmy, whatever.