I had the Dakota with the 5.2L pulling my former trailer which was about 3500-3800# depending on contents. A friend had a Durango with the 5.2L pulling the same trailer as I had. I have a 5.3 Silverado now, towing my 2003 International.
While I would not advise the 5.2L (or the replacement 4.7L) for towing the International, I am quite sure that the 5.9L in the Durango would pull the International quite handily. The vehicle itself has plenty of heft for the traiiler and the short rear overhang should make up for the short wheelbase.
I don't know whether Dodge's new 5.7L is available in the 2003 Durango, but that would obviously be my choice if it were.
John W. Irwin
2005 Classic 28 "Sabre-Dog III"
2013 Silverado 2500HD Duramax/Allison LTZ
WBCCI #9632, TAC TX-10