The OP stated that the truck GVWR was going to be several 100# over with passenger and dog in truck, not over GCVWR. With over 40 years of legally loading trucks of all sizes and combinations, it is all about where and how the trailer is loaded. To take weight off the hitch/truck move weight in the trailer from the front to the rear. If necessary add several hundred # to the rear and that will remove several hundred # from the truck/hitch. Very simply put it is the teeter totter principle. Heavy person on one end lifts lighter person on other end.