Typical capacities for a 1/2 ton receiver hitch are:
500 Weight Carrying (no WD hitch)
1000 Weight Distributing (with WD hitch)
Here's a way to get a good idea of what you can really tow:
1. Take the payload capacity from your yellow door sticker.
2. Subtract the weights of your wife, children, dog(s), any tools you keep in the truck.
3. That will be your tongue weight, or 1000lbs, whichever is lower.
4. Multiply by 7.5.
Generally speaking, you need a minimum of 10% of the trailer's weight on the tongue for stability, but travel trailers usually need more and run in the 13% range.