The weight of a 28 foot travel trailer depends on the materials the travel trailer is made of as some travel trailers weigh more than others.
Most 28 foot travels trailers though weigh between 4,000 lbs to 5,000 lbs which is just the weight of the travel trailer itself without the tanks being filled or any of your luggage or gear inside the travel trailer.
A 28 foot travel trailer usually requires at least a 1 ton pickup to pull safely although a smaller 3/4 ton pickup truck might be able to safely pull the 28 foot travel trailer.
I would use the heavier pickup truck to safely pull the 28 foot travel trailer as it's much better to have a bigger truck that can pull the travel trailer more safely.