Ok - this decision has changed to 3/4 ton or 1 ton?

For a slide in camper, do not even look at any truck with less than, at bare minimum, 2,600 lb. payload capacity, even for the lightest of hard sided campers. The one ton truck would be best suited for a truck camper, and the dually would give much more stability than the single rear wheel version, as well as more payload capacity. Which ever one you decide on, make sure it has a rear stabilizer bar.