My F-150 has a max cargo of 1411 lbs. My 5000 lb dry weight TT is 6400 lbs across the CAT scales when loaded for the road.
The tongue weight is 750 lbs and my family and gear are right around 600 lbs. So my truck is at or near its max cargo weight.
We have towed 40,000 miles in 5 years and would not change a thing. The combo works great. But do not kid yourself, it is a lot of wear and tear; compared to just hauling air or light loads most of the time.
Our TT is 25 feet and perfect for winding through city streets to find shops and local attractions. But the next most important thing is the floor plan, it has to be right for your family.
Good luck.