IMHO, ordinary, standard, EAS ('Boge') dampers work best with airbags. - That's what they were designed for... Works well for me.

IF you need to tow or carry humungous loads, then quite frankly, the endless rounds of modifications will see you poorer than if you'd bought a more suitable (4wd truck?) vehicle.

Or modifying your driving style and cargo-expectations may be cheaper & easier. Eat minimal grains/carbs/sugars, more protein and fats