I figured I would share my experiences with putting a Brake Controller on a 2014 JGC Summit. I have inscluded some pictures for ease of reference. I am doing a little towing trial on a Demonstrator vehicle so I have not perminantly attached the controlled but I note how.
First off, this was super easy. In comparison to the 2011 Durango the Plug in adapter is way easier to access in the 2014 Jeep Grand Cherokee (Durango the Connector is above the programming port on a hard angle). I have also included The Hitch Cover removal (Thanks to Silvermax04 for the assistance on that)
Pic #1 I highlighted the Controller Plug in with a red circle (behind the brake pedal cliped to a wiring harness facing down). I dropped the hard fabric cover for the shot but it is so easily accessible you could do it without. You may want to anyway for cable routing.
Pic #2 / #3 The Mopar Jeep/Durango plug in adapter from Chrysler Parts for my Tekonsha P3. I show it plugged in with the shoft cover in place for reference.
Pic #4 Towards the console side there is a screw holding the dash. As I prefer not to drill holes into my new JGC when I get it I will get a slightly longer screw and some washers to extend this as one side of the Mount for the Controller. I will use a slightly oversided screw to hold the other side into where I will remove the Plastic push clip (spacing is good). The way I only need to make one small hole in the soft fabric and no holes in the dash
Pic #5 If you have a summit this cover is not easy to get off the first time. Undo the thumb screws on the bottom, once both are loose you can pull down on them a little to feel where the cover ends. If not you will be pulling on the bumper instead and won't go far. I found that once you got your hand in their you could squeeze up like the picture I have here on both side evenly and you pulld down and slightly towards yourself. If you have it pulled a little towards you which you can see the way I have it tilted, it comes off OK. but not easy.
Pic #6 You can see this is the exact angle it was easiet to pull down. It is not straigt down, but kind of towards you.
Pic #7 Picture of the clips holding the bumper in place. There are 4 and they are only along the top. They are made of plastic which is why I likely wouldn't be taking this on and off per season. You can see how long they are so don't try and band the cover up while pulling off or they will break.
Hopefully this helps.