5300 lbs. with a proper hitch (i.e., proper height for weight distribution). Keep the width of the trailer nearly the same as the truck. I don't recommend anything wider than six feet, and six feet is pushing it as is, especially if the trailer is longer than eight feet.
I haven't towed anything substantial per se, but do pull a 5x8 mid-side trailer that has a capacity of two tons. I haven't maxed out the tonnage, but around 1-1.5 tons, the Trac was capable. Just expect lower gas mileage and the ordinary concerns--proper braking distance, a hard-working engine when climbing mountains, etc. I see you're from Scranton, so probably you're more than familiar with I-81's climbs when going south through Hazleton or north towards Syracuse.