A one to truck will have a cargo capacity of 5k to 5.5k tons. Any weight you add to that truck will reduce that capacity. Check the capacity for the particular truck you plan to buy before you commit. A one ton may not be sufficient depending on how much else you intend to carry. Our camper is 2900 lbs dry, and loaded up we're close to the limit with a one ton.
Definitely air bag it, and an onboard compressor with controls near the driver seat is well worth the extra money. DuAlly's add weight to the truck, and reduces cargo capacity. I'm not sure if they increase the capacity or not. They're nice to have, but double check if they're going to help or hinder the weight concern. Same with four wheel drive - the extra weight reduces capacity. Do you need it?
Just some thoughts for you to consider.