When i worked on a concrete crew the owner found a old chevy 1 ton duelly with a dump box. We would only use the truck to haul sand or toss the power trowel in the back. There was a gooseneck hitch in it and we would pull and tandom axle dump trailor. I remember many times going up hills with the trailor loaded with all the scrap that was leftover from house builds. Even though it was a very tuff 327 chevy with a 3 speed, it would pull the 18ft trailor up hills only with your foot in the carb, you would lose speed abit but never had to downshift. Had very good trailor breaks for stopping. Never had a box tie down on the front, and to my knowledge even pulling the trailor around jobsites.. ruts, and hills, not yet lanscaped the truck box never came up. But since your pulling a triple axle, i would might suggest having dump box tiedowns regardless and make sure you have them safety chains very well made just in case. The goosneck ball was located about 1 ft in front of the rear axle