I tend to go with 9 free links with the 10th link in the chain saddle. I show 2 1/2 links between the spring bar and the bottom of the rotating bracket. The spring bars are slightly above parallel to the frame. This seems to give me the best ride. However being this tight accelerates the wear on the u-bolts connecting the chain to the bar. I ordered replacement u-bolts from etrailers and will be replacing the old ones next week sometime.
I have never felt comfortable using the supplied wrench. Almost skinned my knuckles using it. I use an 18" breaker bar for more leverage and a better grip.
I always raise the bottom of the coupler to 25" above ground level to relieve the tension on the bars. Fewer surprises that way. Often times the tension is so low that I can practically rotate the bracket by hand.
I am happy with my Sway-pro.