mmsafd... Yes get them. Just like what was said go EGR. Nothing like "VentVisor" brand, EGR are very simple to install and they will be straight every time. VentVisor use tape on the body and takes a bit more time to get them straight and if you live where there is really hot sun or you like going at high speeds, the tape likes to come off near the lower section close to the mirrors, that is not a problem with EGR.
For some reason I am thinking that EGR still has the tape type, if I am correct on that make sure you ask for the "in channel" visors.
But me... If I had a CC (well I do have a 3500 and yes I have EGRs on that truck), I would still like to have the back also, if for anything to match it up to the front... To have cross ventilation you can't beat having all 4 windows cracked open.