I almost did the tow mirror swap from the 3rd gen, but I didn't want to hassle with finding two sets of mirrors, putting them together, and all for about the same cost as just buying a new set of CIPA mirrors. And the CIPA mirrors are considerably larger then the stock mirrors.
I am not sure which stick out further, but mine are good enough to reach around my wide trailer, and the trailer is pretty close to the cab with my setup.
I still like the factory look of swapping the 3rd gen's on. But I wanted simple, and larger.