Hi, I to have a gooseneck I pull around every once and a while. There are two types of hitches that I have seen, and they both have about the same amount of adjustment. I adjusted mine down to get it as level as possible, with out being to low as to cause interferance problems with the bed side rails. I guess it depends on the type of terrain you pull on. I wouldn't feel comfortable going any lower then 5" off the bed rails. I think 6-7" would probally be a more popular figure. The key is too with any trailer, get them as level as possible. Usually with a TAG, or bumper pull trailer this is not a big problem, just get the right drop ball mount. But you are limited with the gooseneck. The key is to get them as close as possible, this distributes the weight more evenly on the trailer axles. If you are unsure about how low you can safely go. Just take it down one hole at a time, drive around alittle and see how much room you have on different road conditions, that way you can't mess up. Good luck.