With the 4.7l engine... I would not want to tow that trailer you have in mind with that engine..
You have to include the passengers when you consider your truck weights.. Not the trailer weights.
That #500/#5000 on the hitch is just the weight carrying limit for that hitch. If you use a WD hitch, it will have a higher trailer weight rating, but you will still be limited by your truck, no matter how much the hitch can handle.
Lots of numbers and weights get thrown around here... It does not all just equal what the paper work says.. So, just gotta do what you gotta do..
Good luck!
Mitch