I ran the CIPA slip-on mirrors on my 04 for a few years, they did a good job. Then 3 years ago I bought a pair of factory mirrors, they a night and day difference from the CIPA mirrors, there is no comparison between the two. The factory mirrors are MUCH more stable and the visibility is great, don't get me wrong the CIPA mirrors did the job, but now that I upgraded to the actual towing mirrors there is no way I could go back to the CIPAs.
Even though it appears that the power towing mirrors for the 2105/16 are either hard or almost impossible to find I would still go with the aftermarket non power units over the CIPA, especially if most of what you use your truck for is towing.
TT-2013 Passport 3220BH
TV-2004 F150 FX4, not exactly stock...
with 2001 Kodiak K215: 2010-10, 2011-12
with 2012 Grey Wolf 26BH: 2012-19, 2013-24, 2014-11, 2015-6
with 2013 Passport: 2015-13, 2016-15 booked