So I drive a '13 JKU and I intentionally opted out of a head unit with the navi feature because I like the user interface and functionality of my google navigator on my cell phone (galaxy S4).
But I got tired of putting the phone in the tray on top of the dash. The phone never stayed vertical when I turned and if I placed it horizontal, too much of the screen was blocked.
So I decided to get a cell phone mount. I had two requirements. The cell phone mount had to work with my otter box defender series case and I didnt want to have to deform my dash or screw anything in. Much to my chagrin, I didnt really find any product I liked. Some products fit my cell phone, but they looked cheesy or cost > $50.
So, being a Jeeper, I decided to fab something up myself. My defender otter box came with a belt holster made from sturdy plastic. Seen here...
Now, I was never going to use the phone holster for it's intended purpose, so I decided that I'd remove the belt attachment and use this for my cell phone mount. I took a thin flat head screw driver and pried the belt attachment off. There was a little bit of material left in the middle of the back of the holster, so I dremel'ed that off too. Here is what the holster looked like after I removed the belt clip (note I was not too concerned with making it pretty because it will eventually be covered up by the navi mount).
I now needed a generic suction cup, and surely I wasn't going to find a suction cup with a flat plate, so I just bought a garmin nuvi mount off ebay for $6, seen here...
I took a Dremel and cut off the angled parts of the Navi holder. After that, it looked like this.
I then took an adhesive and applied the adhesive to both the flat piece I just created as well as the otter box holster. I let the adhesive cure overnight and came back the next day. The holder works great and it allows me to see the whole cell phone display, problem solved!
This mount only cost me $6, since I already had the otter box and adhesive.
Consider something like this for your rig if you're looking to mount a cell phone or other gadget to your windshield.