Here was my remedy for the exact same issue---with my Cox--I did the same thing--I adjusted the rollers everywhere--this is how I handled it--and it works--I power the boat on after sinking the trailer a bit over half way and it centers every time. First I mounted the boards and covered off of rough measurements and then loaded the boat and then had to jack up the boat and move the boards a hair to get everything where they needed to b and the boards bow just right to support the boat fully
, and walah--perfect and would never go back.