Not only bed rail clearance needs to be addressed, but =pinbox= clearance does, too, in some cases. How many times have we read about people having to clip the rear corners of their pin boxes to keep from hitting the =inside= of the bed rails when turning? More'n a few. You can only raise the pinbox so much before you might start having =this= issue. Something I didn't know of when I first started out and, fortunately, didn't have to deal with. Personally, I'll take 2-3" nose high rather than losing bed rail clearance.
Lyle