7000 lb loaded is the upper end of the tongue weight limit if not over depending on how you load. Some use the nicer, heavier hitches to control the larger trailer, just remember the weight comes out of both the tongue weight and payload considerations.
After that you will have between 600 and 900 lbs of payload depending on the truck. (my 07 has a payload of 1745 lb, 03 1565 lb)
Out trailer is 4200 lb dry with a 7000 lb gross. We have it loaded down pretty well and always travel with a full tank of water. We were considering upgrading to a trailer with a 5500 dry weight but that would be it.