Been reading this with alot of interest..
But I have been thinking along a different idea..
Instead, replace the unit with a nice 5" LCD with HDMI, VGA and composite inputs..
The LCD wouldn't be a perfect fit as there will be a gap above/below the LCD but it will be of a higher resolution than the CID (800x480)..
I has thinking then the HDMI input can be connected to an Android stick MK802 or Eqiv, Composite to the reversing camera and maybe the VGA from a SBC or microchip PIC controller..
The stereo would have to be replaced, and currently this design wouldn't show any fuel consumption info or details about any faults/failures/fluid lows..
RE the PCB method above, A company called OSHPark in America do prototype PCB's $5 Per Sq inch for 3 PCB's.. So 100x50 is approx $40 (£23.65) for 3, £7.88 Per PCB. Great quality PCB's too..
Carl,