regarding the question of the stable loads taking over if you have a bag failure: I had a tread separation at freeways speed. the resulting destruction of the wheelwell area ripped out the filler lines for both bags and as a result both bags went to zero psi. the stable loads (uppers only) allowed me to make it 500 miles home without damage to the bags. I was able to redo the lines and the bags are still in service two years later.
I have both upper and lower stable loads on my new dually and I have airbags for releveling when I have to tow the horse trailer, otherwise I run my bags at zero psi as the ride with both sets of stable loads is perfect with just my Lance 1055 in the bed. With the 7000 pound horse trailer I need the airbags.
https://www.airliftcompany.com/products/air-springs/loadlifter-5000-ultimate/