Do you have a picture of the set up so we can see the sag?

 

You do have a weight distribution hitch, right?

 

Throwing multiple suspension aids together on a truck is, IMO, a recipe for disaster and wasted money.
RAS can be used to take care of rear squat that the WDH (weight distributing hitch) MAY not take care of, BUT…
the WDH should be enough if sized and set up properly.
I added SumoSprings to mine to lessen squat when NOT using my WDH, but I got them used for a savings.
The RAS appears to have the added benefit of acting somewhat like a roll bar on the rear suspension.
The Sumo Springs don’t engage unless the truck is under load, otherwise they just replace the jounce bumpers. I like the concept because it’s set & forget, works when needed, no messing with settings for various loads.

 

Yeah as mentioned if your hitch set up is correct then you shouldn’t be asking about suspension aids.

At minimum if you need suspension aids you need to be scaling and considering your tire ratings.

 

Thanks for the suggestions.