I went from an 08 ram 3500 SRW 4x4 to a 14 ram 2500 4x4 (love the coils) with FS airbags. Standard pin box and B&W companion. Both have adjustment. I moved the head down and back and didn't need to mess with the pin box. I pulled a 14 Wildcat 313 several thousand miles, my current rig is a Silverback 29 RE. I pulled a buddies Columbus 38 somethingorother without issue as well. 5 psi gives me a full squat and level rig. 20 or 30 psi brings it back up to normal. The nose maybe slightly up (or it may be my imagination). I don't have six inches of clearance. Probably closer to 4.5. Zero issued. I am running about 34' and of course a longer rig would be more pronounced nose high.
2014 Silverback 29RE, 2014 Ram 2500 CC 4x4 Hemi 6.4 auto w/ airbags, B&W Companion. Saltwater boats and rum like any good pirate.
Lose the 2nd and the rest will follow.