This is my brothers 05 F350 4x4 6.0 auto with 36' tri axle. We were rolling about 24'000lbs in this picture. I have a 97 Dodge 3500 4x4 Cummins auto and routinley weigh 20-24,000 lbs. My GCVW rating is 18,000 lbs With my pickup camper and my enclosed tag trailer I weigh right at 20'000 lbs with the gooseneck and 2 Jeeps I weigh about 22-24,000 lbs depending what other gear I am carrying.
I had a 89 Ford 250 std cab 4x4 7.3 5sp that had a 8,800 gvw, the truck weighed almost 8,000 lbs empty. This truck weighed around 20,000 with my pickup camper and enclosed trailer. It was a white knuckle driving rig. I had plenty of power but not enough truck mass to hang on to that much. (truck lenght, # of tires etc)
It really comes down to how your truck and trailer are set up, what you are comfortable in driving, and how much you want to exceed the manufacurers spec.