Cattleman makes a wheel-to-wheel full board with the flare for the dually fender. There's another full running board maker on the market for sure, but I can't remember who it is offhand.
I have a W2W "nerf bar" on my CCLB that goes wheel-to-wheel, but it's a SRW. I think it's a Big Country, but I'd have to go look.
Is yours a LB or SB? I've seen plenty of photos of CCLB DRW's with a standard W2W bar that gives enough overhang to be useful, but I don't think it works nearly as well on a SB DRW.
I went with the basic nerf bar for my LB SRW, but if I had gone with the DRW, I would have done the Cattleman HD with the dually flare. They are pretty heavy though.