Local truck shop did a search for me and couldn't find what I want. My fingers are going numb looking on the internet! I have a 2012 crew dually with the 8' box. I have a friend with an 06 Chevy in the same config and he has running boards that flair out in the box section to the same width as the wheel well. They run the full length from the back of the front wheel well to the front of the rear wheel well. They are two piece with the break at the cab/box joint. Anyone know who makes these? There are no markings on my buddies to track who made them. 
