The so called "Tow ratings/capacity" are as big a joke as dry weights. You will never be able to tow up to your tow capacity as you will run out of payload by hundreds if not thousands of pounds before you even get close to max tow.
As a general rule of thumb figure 75 - 80 percent of of your tow capacity will get you into the ball park if you do not load too heavy. My F-150 SCab {5.4L V-8} was rated to tow 8,600#. When towing our 5,600# TT we were within 200# of our max payload.
Beware of Crew cabs and 4 X 4 as they are heavy and notoriously short of payload. Don't forget to add the tongue weight {roughly 13 percent of the loaded trailers weight}+ another 100# for the weight distribution hitch. Those numbers come right off of your avaialable payload before you load an ounce.
:C