I have a different truck now and don't run bags, but when I had my F250 CC V10 4x4 and my Saber 34TBOK with approx 2500lb pin weight, I ran about 55psi loaded. Had them as high as 60 and as low as 30 while towing. Empty I'd shoot for 10-12psi.
Joel and Teresa
2016 Sabre 34TBOK
2006 GMC 3500 CC LB DRW 4X4
I have the 2007.5 Dodge 2500 with Air Lift bags pulling a Wildcat 327re with about 1600 pound tongue weight unloaded. I have played around with the pressure a little and I have found that about 28 to 30 pounds gives me the best ride on rough roads. I leave it around 10 unloaded.