Welcome to the forum!
Looks like you should be fine. Just take it easy in the mountains. Does the Durango have a transmission cooler as part of the standard equipment? If not, having one added would be a good idea and not that costly. I agree with carrying a little bit of water as it comes in handy if you stop and have lunch in the trailer or want to use the bathroom. And, adjust your tire pressure as per the owners manual. Usually, you can inflate the rear tires to their maximum or a few lbs. under. I would also check to see what tires are on the Durango and are they they the highest rated for weight if different sizes are compatable with the Durango. Make sure you have a good weight distributing hitch and that it is properly set up, which means you want to take it out for a good trial run well before you leave on your trip.
I wouldn't make the trip to the Rockies my first trip with the Durango and trailer. Take at least one short trip beforehand to make sure all systems are working and you're pretty much confident that you have everything that you need. I suggest having: 1. a power cord extension, same grade as the one that came with the trailer 2. at least 25' of water hose 3. an extra sewer hose and needed fittings 4. a basic tool kit 5. extra fuses for the trailer - see what's in the converter
Finally, always check the power at a campsite FIRST! You don't want to get unhitched and then discover that you have no power. Also, you may want to consider a Progressive Industries PT30C 30 Amp Portable Electrical Management System. They're not cheap, but cheaper than paying for repairs to your AC, television, microwave & refrigerator if there is a problem with the power. There are alternatives such as a basic surge protector, but with the better magagement system, you have protection against high/low voltage, improper grounding, etc.
So...once you're ready to go....have a great trip and enjoy!!