While a 3/4 ton truck can safely tow a 12,000 pound travel trailer with a 1,500 pound hitch weight rating, your truck is limited to only about 8,000 pound fifth wheel with a 2,000 pound pin weight. That is a mighty short fifth wheel. . ..
Your truck is probably rated around 2,200 - 2,500 pounds of total cargo. Assuming that the kids and wife ride in the truck, that leaves about 1,500 pounds for the hitch weight rating, and then you will reach the maximum GVWR of the truck.
With a 2,800 pound empty pin weight, and a 150 pound hitch, then you need to add what water weight might be, and anything in the forward closets to the empty weight of the trailer. You will end up with about 3,500 pounds in the bed of a dually truck with that trailer. On top of that 3,500 pounds, figure about 500 - 800 pounds of passengers and anything else you might want to add to the truck while camping (generator or bikes, ect). Your total cargo rating needed will be in the 4,000 pound range, perhaps a little higher.
Fred.