I understand what you're trying to do, but that may be kinda hard unless the pad is perfectly level. As and example the campground we're in, I'm nose low due to a slope. The 382 behind us is nose high due to the same slope.
Maybe tell us what you have for a truck and hitch and we can get closer to the answer you're needing. I moved both my pin box up one bolt hole and my hitch down 2 bolt holes in order to get the 340 level with the truck and still have enough clearance between the top of the truck bed rail and the bottom of the overhang of the 340. Overhang, I know that's probably not the right word, but I don't know what else to call it.