Absent of facts we can all have our guesses.
Being the fat cheeks are above the floor and forward of the door it affects only the cab. Have you considered the extra width to be an early rendition of a comfort cab? A well placed bump out could provide just the whatever space needed.
Added width over the truck would have minimum impact on curve overhang.
Check out the Jeep critter parked in the lot adjacent to the big blow.
