Re: OOPS!
The 1/2 ton pickup probably has a towing capacity of around 6500 pounds (4x4 and extended cab are heavy options). But check your manual or other source to find out for sure. Just be aware that the towing capacity is for no accessories, no cargo, no passangers. Just a 150 pound driver and a bit of fuel. You need to subtract the weight of anything else in the truck from the towing capacity. Plus, that towing capacity is for a loaded flat bed trailer with 'no' wind resistance.
So, generally it is best to not tow much more than 5000 pounds with a 1/2 ton vehicle (some of the very newest models seem to have more capacity). Plus, a fifth wheel puts a lot of weight right over the rear axel, and many fifth wheels will cause a 1/2 ton truck to exceed its maximum rear axel weight. Generally you can pull more travel trailer with a 1/2 ton vehicle than you can fifth wheel, because the travel trailer design tends to transfer less weight to the tow vehicle.
Any way, the dry (empty) weight of the trailer will probably be a bit much for your truck, and you will want to carry at least some water, some food, some clothes. cords and hoses to hook up with, toys to pass the time with, some tools to fix basic things which go wrong, cleaning supplys, leveling supplies, etc. I would say that it is likely that you will sometimes be at 7000 pounds or even more when traveling, and that is really more than that truck is likely to be able to handle.