Keep in mind that the weight specified by the trailer manufacturer is usually dry weight. That means weight when empty. You can easily add 1000 lbs to the weight of a trailer by the time you've filled up the water tank, added dishes and personal effects.
In that case, you're right up at the 5000lb towing capacity of your truck. Also, don't forget the Gross Combined Weight Rating of your truck. Often, you'll only be able to use the maximum towing capacity with the actual truck itself lightly loaded. Put 4 people in the cab, and load the back with a bunch of suitcases, hook up your 4500lb trailer, and you could easily pass the GCWR. One of the many disadvantages of compact trucks....
That being said, if you're only going to tow your trailer a few times a year, then no problem. If you're planning on living in your trailer while moving around the country constantly, you're probably better off with a fullsize truck with a small V8.