Using a much heavier Equalizer hitch than is required can do some damage to some trailers. Airstreams are a good example. When the hitch is too rigid the shock can be transmitted back to the trailer and since an Airstream uses its shell as part of the structure of the trailer, it can actually crack some aluminum panels.
My trailer has a GVWR of 7200 so the 6K bars were out. With the 10K bars I am in the right area. I wouldn't want to step this up to the next level.
The advice to call the company is the best you will get. They know what they are talking about and will steer you in the right direction.