Since this is a gooseneck (or maybe a 5W?) rather than a conventional hitch trailer, the WD tow rating doesn't apply. And the 3.42 axle is less capable in pulling power, but for a one-time, 100 mile pull, that's not a big concern.
However, a gooseneck or 5W puts a lot of weight on the truck, typically 20-25% of the loaded weight. That's likely to be upwards of 1100 lbs even with an empty trailer, and more than 1600 lbs if loaded with gear for the campsite. That will likely flatten the suspension of that truck, and may even lift the front end enough to make steering dicey.
Could you elaborate a bit on the type of trailer and hitch? You used the term "gooseneck travel trailer", but those are technically contradictory terms. A travel trailer has a conventional ball coupler type hitch that attaches at the back (bumper area) of the truck; a gooseneck couples to a ball located in the center of the truck bed; a 5W has a pin that slides into a flat plate mounted above the truck bed. The towing needs and safety vary tremendously among these types.
Gooseneck hitch photo: http://www.turnoverball.com/support-and-resources/our-blog/towing-and-turning-part-2-equipment-that-makes-it-easier