A few more things to consider. I finally loaded up my 2018 3500 and went to the scales with my 35 ft Fifth wheel. I had added up all the additional weight and thought I was good but when weighed I was 220 lbs over my rear axle rating (7,220 lbs, have a 7,000 lb axle) but good on the front axle (5080 lbs, has a 6,000 lb axle) and tires were good rated at 3,640 lbs ea. This also put me over my GVWR by 500 lbs. I then made a rack off rear of fifth wheel, relocated the generator that was in front compartment of RV to rear rack as well as the gas cans that were in bed of truck, moved the ice chest and other items from bed of truck to inside RV behind axle and weighed it again. I am now at 6860 lbs at rear and 5260 at front (still 320 lbs over GVWR of 11,800 lbs but good on both axles). I then realized my 90 gal fresh water tank (that was not filled during weighing) is located behind the rear axles of my RV. I filled the tank (adding approx 700 lbs to the trailer weight) trailer now weighed approx 15,000 lbs (truck rated to pull 24,646 lbs) but got my GVWR under the rating. Just get creative and redistribute the weight.
Additional info: 2018 Ram 3500 HO Diesel rated (by vin) Towing of 24,646 lbs and Payload of 3.860 lbs, Fifth Wheel Dry weight 12,400 lbs with hitch weight of 2,600 lbs.
when weighed had full tank of gas, myself, wife, dog and other misc in truck.