Towing Shouldn't Be This Difficult - Help Needed

I've never used a hitch like that but I asked how does a person know how to adjust them. I was told from a couple of people that have used them to measure your space between bot of rear fender opening and the top of the tire unloaded, then adjust that when loaded to about 1 inch less. Also make sure your tires have proper air preasure, if their down some that will also give you a wandering feeling even when unloaded.