The air bags shouldnt be used to help level the truck unless it is to put it back where it was before loading it.
Meaning unloaded, if you want the truck level it should be done with, block, add a leaf, extended shackle or a replacement spring pack and the bags set at 5 psi. Any more than that and it will ride harsh.
You have a 6" procomp on a crew max, as built with the lift they never sit level as it was designed on a double cab. I would start with an extended shackle. You may have to get a spacer for the air bag to get it to sit right with the extra lift.