I agree you should look at a pop-up camper to keep the weight down. You should try to find one made for a short bed truck also because even though you can drop a long bed camper onto a short bed truck with the tailgate down, it'll put the weight behind the rear axle. Trucks don't steer very well if the front wheels are bouncing off the ground.
Because you'll likely be overloading your truck, you should make sure you have good E rated Light Truck tires on the truck and keep them well inflated. Check www.trucktires.com
for a tire inflation table. If the back end of the truck sags too much with the camper loaded, you'll want to add overload springs or helper springs or Timbren springs or the best choice - airbags. Airbags are great because you can adjust the ride height.