A photo or two or more would really help. Closeup of the WDH and the TV & TT hooked up. Pending more info., you really must have setup issues with the Reese DC.
Where did the 700 lbs for tongue weight come from? Was it calculated from doing 3 separate passes through the scale? If you did the three separate passes correctly, you could calculate the weight distributed between steer, drive and TT axles which would be very helpful info.
The drop in the rear of truck sounds okay but you need to measure the before and after front fender heights. Sounds like you may not have done that yet?
So if it is the dual cam, you need to pay more attention to how it needs to be set up and adjusted. I have yet to read about a dealer who got it right from the get go. How the cam arm brackets are mounted to the frame is important too, but won't cause sway.
Yes, where the cams ride in the "detent" of the spring bars is very important. They should be dead center with the TT & TV in a straight line and you can easily check. If the dealer mounted the brackets in the correctly, there should be room to move the cam arms forward and back with the big nuts.
My experience with the DC DWH is when we initially started out with 800 lb bars on our DC before upgrading to 1200 lb bars. The actual scaled weight of our TT was way higher than anticipated based on the dry tongue wt. 800 and 1200 lb bars are slightly different length. The 1200 lbs are about 1/2" longer. I installed the cam arm brackets 19 3/8" from the center of the hitch ball to center of the end of the cam arm brackets as per Reese specs. BUT... This did NOT leave any room for adjusting the cam arms and the ends of the arms were tight up against the through bolt in the bracket. Going to 1200 lb bars gave me lots of adjustment room.
I would see if the cams are riding correctly in the bars. Check the distance between the hitch ball and through bolt on the bracket, and if there is any adjustment space left on the cam arm bracket.
When the DC WDH is properly installed and adjusted, it is awesome and definitely worth the trouble of fiddling with it. Funny, in the 2 seasons that we've had our DC hitch, I have not seen a single one at a CG anywhere. I keep wanting to find one so I can find out somebody else's experience in person.