Something is amiss I think.
I have a 2010 F350 SRW XLT PS CC LB and find the uppers are very good and I don't really need the lowers. Engaging the uppers brings in a heavy overload spring as soon as the camper is on the truck and I could do away with the air bags (though I do use them with about 20psi in them but still am not sure I need to. I've had them as low as 10 and as high as 30psi and still can't see the difference).
I can engage the lower stable loads but the lowers engage with the AF990 on anyway so really it's just keeping them engaged during spring travel over bumps etc.
The sway and rock have more to do with the shocks not handling the heavy weight so I added Rancho 9000's (adjustable)and it's a BIG improvement. I also added the Hellwig BigWig rear swaybar which helped even more. Now I'm very happy.
If it were me, in order of what I think made the most difference this is what I think would be worth doing:
1. Make sure tires are up to the job
2. Upper Stable Loads
3. Heavy Duty adjustable shocks
4. Heavy rear sway bar
5. Lower Stable Loads
6. Air Bags -- mostly for towing so you can keep the truck level or when you need to level with a heavy camper.
Your rear end on an F350 is set by the factory 2" higher than the front. This is normal.
Here I am with a camper that is 1000lbs heavier (or perhaps 1500 if your weights are scale weights and accurate -- don't go by what the Manufacturer tells you)
