Douglas,
Ignore dry weights and what the manufacturer says are pin weights. Go by gross weights only and figure on 20 - 25% (probably closer to the 25% end) of the gross weight for pin weight. Most 3/4 ton trucks will run out of payload (what's left over for pin weight after you have fuel, people, pets, and stuff in the truck) WAY before they hit the gross combined vehicle weight rating or max towing capacity. Search this forum for the topic - you will find dozens if not hundreds of threads on the topic. To do it right - and safely - requires weighing the truck fully loaded and calculating all the numbers. Many full-timers/old-timers will tell you to choose your RV then work back to how much truck you'll need to tow it. Above all, be safe.
Rob
