Of course you can set up the WD with the Dual Cam system installed. Once you have the WD where you want it, just adjust the Dual Cam arms so the cams ride in the exact center of the bars when they are drawn up.
The problem some people have is that they are not careful when installing the cam arm brackets on the A frame and then when they try to adjust the cams to fit exactly into the V of the bars they run out of adjustment on the arms. I would do as you have done. Install using clamps to hold the brackets in place and simulate as best possible the position of the WD bars so you can know exactly where to put the brackets before you bolt them in place. Make sure the cam arms are adjusted about 1/2 way on the arms before installing so you have adjustment room both ways.
Now you will be able to get the WD how you want it and still be able to adjust the length of the cam arms to center the V on the cams. :)
By the way, I think the 1" rise ball would be plenty. Going too high can bring other problems and may place too much stress on the hitch head via leverage. I also agree with your choice of using the welded head. Compare the lower trunnion mount sockets between the two and you will see that the welded head has much beefier sockets. There have been problems of trunnions breaking out of the lower mounts on some of the cast heads. I don't know if that one you have is one of the problem ones or not. You could probably do a search on it. JBarca has several posts on it, including model numbers to look for.
See here.Barney