I did have the rear leaf pack looked at by Deaver Springs in Santa Ana, CA, an industry leader in the repair/manufacturing of spring packs for the aftermarket industry.
On their recommendation, I added a single leaf to each rear spring pack. With a coil front end there is not much I can do.
I don't sag at all, the backs are much better with the new pack, but the fronts need the better shock.
Sway-bars will not effect the change I am looking for.
I don't believe that any shock bought off the shelf has the extreme valving for the applications a HD truck camper set-up needs. There is just no reason for those companies to make them as they will impart a lousy ride for the mass market. Rancho's adjustable are IMO, still baby steps.
Hopefully there is a reason FOX/KING shocks are priced where they are at, I'll soon find out.
Can't knock-em till you've tried-em.