Not following the whole topic, you are fixing the axle overload by adding air bags, upper stable loads and lower stable loads?
I was never admire of lower stable loads since they apply shear forces to leaf spring, but you should not have 3 systems to deal with overload.
When my 2017 Ford doesn't need any modifications, I was carrying 10k lb loads on my F450 and air bags was all I needed.
So if you don't like ride with air bags, maybe add a spring or timbrens or other mechanical support should do?
When stable loads might help with some issues, there is a limit how much you can pull from factory suspension.
