1. Get the dual cams installed and working.
2. Be sure the trailer is level front to rear before you hook up to the tow vehicle.
3. Adjust the hitch so the top of the ball is about 2" higher than the top of the coupler before you hook up to the tow vehicle. IOW, the tongue should be about 2" higher than level before the weight of the tongue goes onto the ball. The tongue weight should then push the connection down so the trailer winds up level again after you connect the coupler and hook up the spring bars. (Depending on the truck suspension, you may need to use something different than 2" to work out to a level trailer when hooked up.
4. When properly adjusted and connected, the spring bars should be parallel to the A-frame of the tongue, which should be parallel to the ground when the trailer is level front to rear. That probably requires using the center link in the 9-link chain
5. If you are not distributing about 25% of the tongue weight to the trailer axles, and about 25% to the front axle of the TV, then you need to mess with the angle of the ball mount where it bolts onto the shank. That requires removing the ball mount, disassembling the ball mount from the shank, then putting them back together at a slightly different angle (maybe only one notch different on the adjustable ball mount).
6. Using a 15" lift bar (I use a 15" length of 3/4" pipe), there should be no great strain for an adult male to tighten the chains up to the proper tension so the spring bars are parallel to the ground and the A-Frame of the hitch.
7. I hope your spring bars are rated for 800 pounds tongue weight. It doesn't really matter what the spring bar rating for gross trailer weight is, but the tongue weight rating matters. The Reese Strait-Line dual cam WD hitch I see for sale today is rated 800 pounds tongue weight, 10,000 pounds gross trailer weight. So ignore that gross trailer weight rating and go by the tongue weight rating.
8. If your spring bars are rated for 1000 or 1200 pounds tongue weight, you need to order new spring bars rated for 800 pounds tongue weight.
Here are the ones if your spring bars are trunion style and not round bar style: