Recommendations for suspension mods on a new truck

What he said^^.
That’s why I said, load the camper up before you decide.
Sway bar will help bunches regardless of other mods to increase “capacity.”
But the newer 4th Gen 3500s are comfortable with some serious weight in them just on OE springs.
You “want” it to squat some, like down to level, or at a minimum, engage the lower overloads so it “squats” onto the main leaf overload even if it doesn’t drop much.
Hence the wedges or stable loads. You don’t have a factory upper overload on a srw.