I tried both the k source mirrors and the cipa mirrors. The source mirrors are custom fit for the ford. They do not coverup the puddle lamps or the reflectors on the outside of the mirror. They also fit really well. As the the plastic clips they are not little and are pretty thick so at some point they might get brittle (all plastic does) but I don't see that happening for a long time (at least with my usage) as they can be taken off the mirror why you are towing. The outer mirror does tend to vibrate when I drove more than 45 miles per hour but it was not bad. Your stock mirrors don't vibrate which is what I would be using most of the time. I adjusted my drivers side mirror so that when I looked at it there was a continuation of viewing between the stock mirrors and the extension. I was not able to do that with the passenger mirror because it was a convex mirror to begin with. Since I have never towed with extended mirrors I had to get used to having to decide with of the three mirrors I needed to use my drivers side.
The cipa mirrors did not have any vibration and gave me the extra inch at the top of them. However they covered up the reflector on the outside of the mirror and the puddle lamps. The manufacturer said they do not recommend them for the mirrors with puddle lamps because of the potential for scratching the puddle lamps. I did not see any scratches but the slide on is so tight (a good thing) that there is the potential for scratching the if the mirror housing is not clean.
My test vehicle is an F-150 Lariat withChrome package. It does not have the max tow package so no tow mirrors. My mirrors do have the outside reflector, puddle lamps,and chrome skullcaps. They are power adjustable and power folding.
Neither set of mirrors interfered with the powerfold operation.
2012 F-150 Lariat 3.73 axle
2014 Whitehawk 23MBH