Here is my setup (originally )
And here is the setup I made last night for my Nexus7 over the top of my headunit. *I still have some minor cleanup to do on the bracket edges.
Basically I made a two 3 sided brackets , bottom (resting for tablet), side, front and a top "L" bracket to keep it from falling backwards when accelerating. Then screwed them into the face-plate with very little screws from the back.
The brackets basically create a 1 centimeter cube for the tablet to sit on/in, I used 3mm thick carbon-fiber sheet as material. I also mounted it so that there is a 8mm gap from the bottom so the factory radio buttons are still accessible even with the tablet in in use.
Why make it this way, I wanted to keep the Pioneer unit and backup camera for when I do not want to use the tablet.
I case anyone wonders I use MiFi for my Nexus and or navigation when the tablet is in use. I connect the tablet to the headunit via bluetooth. I even use the steering wheel controls for voice commands and skipping on the tablet and yes my phone is also paired at the same time and I can use the wheel answer and hangup wile the tablet is in. In short when setting up the Bluetooth you have to specify what funtions the tablet has and what functions the phone has (phone = phone only, no streaming audio).
I am using "Car Home" as the Home screen wile in the car
Here are pictures: