I may have been associating your durango with the newer ones, which are pretty small. a 2004 is a fairly large suv. maybe you would be ok. It would just stink if you felt uncomfortable managing it. You will pull it fine. The worry comes with stopping and managing sway. You could probably go longer than 23-24 feet, but 31 might be pushing it. I don't see too many durangos at campgrounds. See more tahoes, suburbans and expeditions/excursions and of course trucks. You have too look at the numbers and figure it out. Dealers will almost always tell you it's fine when it may be pushing it. I'm sure a good sway system will help.