I will get back to the original points of the post instead off all the tangents. T
You asked about the bars in relation to the Reese dual cam on a truck with heavier suspension.
Basically here is the high points of the link Mark posted that goes into depth on the subject.
YOU MUST GO TO A LIGHTER WEIGHT BAR! The DC depends on a firm amount of tension from the bars. If that tension relaxes the Dual Cam will loose its effectiveness.
1000lb bar on a 1/2 ton might deflect 2.5 inches to get the TV and coach level.
1000lb bars on a 3/4 ton may only deflect 1.25 inches to the the heavier sprung truck and trailer level.
We don't need to get into it any deeper then the deflection of those bars.
Now I will explain on the DC system so that people who are not familiar with the DC will understand the point of the deflection and understand the point of this post is not as much about weight transfer.
Here is the instructions for the Dual cam that you can look at to see the design.
The bars on the trailer end ride in a saddle. They do not connect to the chain at all. The end of the bar has a "Cam" bolted to it. Once the system is tensioned up and that the tow vehicle are in line the cam on the end of the bar centers on saddle. The cam ramps off center. Whenever the trailer and TV come out of line the cams fight this change because the cam slide off its center and start forcing the the bars into a higher tension.
So in the instance of sway the DC is always fighting to keep the TV and coach in line.
Here is where the deflection of the bars play in. Think about what happens when you slam on the brakes hard in an emergency. It is a given that the vehicle will "Brake dive" or "Nose dive". The weight transfer of the braking causes the vehicles nose to drop.
Now think about whats happening at the hitch: If the nose goes down the hitch comes up. If you have a lot of distance from the rear axle to the hitch this will be quite a big change.
Remember the amount of deflection to get the TV level between 1/2 ton and 3/4 ton? Well since there is less defection it lakes less change in hight of the hitch in relation to the trailer before the tension on the end of the bars is lost. Without that firm tension the Dual cam system becomes ineffective.
So right when you need the benefits of the DC the most...in an evasive heavy braking situation....the DC stops working because of the lack of deflection.
You need to go to a lighter rating bar with a 3/4 ton truck to make the DC work correctly. Generally a 250lb drop would be about right when going from a 1/2 ton to a 3/4 ton.