I'm not sure what kind of Coilover that you were running, but I chose to simply stick with coil and shock from Carli. I also made the conscious choice to run a 17" wheel with a 37" tire to have as much sidewall that I could get for small bump compliance. The Toyo MTs that I'm running have a 131 load rating ( stock Superduty is 126). I keep them aired down to 50 psi when not towing. with this setup, I don't see how the ride, even with a full air ride suspension, could get smoother.
I'd bet that if you went traditional suspension and then went with an air equipped 5th wheel hitch, the ride would be super stable and smooth while towing.
As soon as the weather clears, I'll send ya a few pics. The S&B tank is more thought out than the titans that I've had in the past. The driveshaft side is nicely scalloped for appropriate clearane and it has effective baffles in it as well. It also happens to be 60 Gallon instead of 55 gallon. and yes, it does take a full 60 gallons. I simply changed the tank size with forscan and havent had any issue with the tank at all.
I spent a ton of time researching how I might build it out. while my use-case ( chase truck) is different than yours, but isn't that much different, so if what I learned helps you too, I'm good with it.