In the past 70 years engineers have learned that ride can be improved by using less leaves. This does not mean removing leaves from an exiting stack. That will make it worse. A 3 leaf spring with thicker leaves engineered from the ground up will improve the ride a lot. And good shocks are a must. Air ride has been tried on front ends with I beam many times, but it was never very successful because of the side to side sway. Air on the rear axle is very doable.