Slow down. You are confusing things.
Tiedowns are to secure the camper to the truck so it doesn't fall off. You need these.
Air bags raise the rear of the truck if it is sitting too low with the camper weight loaded. Even though the payload may say 5600, and your camper is only 4600, the rear of the truck may sag below level under the weight. You want the truck to sit level for best handling.
Sway bar does not replace air bags. Sway bar reduces the amount of side-to-side rocking you get when going around corners. This is especially important with the tall camper in the back. Most heavy pickup trucks do not come equipped with a sway bar so it is a good idea.
Allow the dealer to install the tiedowns. Everything else can be added later if you determine that you need them. The truck will not be unsafe driving without them, as long as you drive carefully.
