The only way the CoG will shift is if the load also shifts like when going over speed bumps at speed and the load leaves the trailer floor which creats a negative CoG … ie. no weight on the bed till the load crashes back down … 
The only way the CoG will shift is if the load also shifts like when going over speed bumps at speed and the load leaves the trailer floor which creats a negative CoG … ie. no weight on the bed till the load crashes back down …