After you tow with it a few times, get back under it and make sure all the bolts are good and tight...then paint it all. This is what I do with a new truck and have never had a rusting problem. Then I check the bolts each spring. The paint not only protects, but it also will let you know if a bolt loosened and the washer slipped. You will see the outline of the washer in the paint.
I remove the hitch in the winter...but it lives in the truck all summer.
I have a tonneau cover.
I use a lube plate, grease on the jaws and penetrating oil on the jaw pins (the vertical pins on the top of the head)in the spring.
I use a tripod, which eliminates the problem of walking into the kingpin.