The weight of a 15 foot long travel trailer can vary depending on what the travel trailer is made from.
A 15 foot travel trailer that is made with wood and metal such as aluminum siding etc could weigh around 2,000 lbs while a lighter weight 15 foot travel trailer made with an aluminum frame and fiberglass siding may only weigh as little as 1,500 lbs.
A 1/2 ton pickup truck is usually big enough to tow most 15 foot travel trailers especially the lighter versions but it's still a good idea to have electric brakes on the travel trailer and an electric brake controller inside the truck.
That is especially true if you're going down any steep grades when traveling as it's best to have brakes.
Also when you add your luggage and supplies to the travel trailer it adds a bit more weight so you need to factor in that weight as well.