I would suggest you look on your driver's door jam for the vehicle specs. You should find the max payload, Axle ratings and GVWR of the truck you actually own not some generic spec book. Go to a CAT scale with a fuel tank of fuel and get both axles wieghed.
- Subtract Truck total wieght from GVWR
- Compare the number above with the max payload
To play it safe most people would say use the lower of the two numbers. Then subtract estimated wieght of other passengers and gear you will take camping. The final number is roughly your allowed loaded tongue wieght of the TT. TT tongue wieghts can vary from 10% to 15% of the loaded TT wieght so for the purposes of shopping take that final number and multiple by 10. This is the maximum trailer you can carry (which generally means GVWR not empty wieght of the trailer)
If you don't have the tow package I would highly recommend the addition of a transmission cooler.
I know it sounds complicated but to really know what you can carry/tow you have to do the math.