Hey, not sure if this will help your decision, but the PCB in this unit is one solid piece (with a small secondary PCB with the cable connector on it).
Wish I had seen this post earlier, as I just had mine apart and I could have taken a few pictures of the unit. You should be able to find some other pictures around on the forums though, if you search hard enough. The MP3Car store may even have some.
The PCB can best be described as a rectangle, with a smaller rectangle section removed, directly below where the connector would hook up. It measures 170mm wide by 115mm high. The "removed section" is 50mm wide by 80mm high, on the bottom left of the PCB, when looking from the back.
Also, the button section of the PCB sits about 13.5mm below the case the screen sits in (this is where the power LED, IR sensor, and buttons are), so you'd want to measure for that where ever you plan on installing the screen.
From memory, I believe the only thing in the bottom section of the PCB are the traces running to the buttons, led, and ir sensor (and I noticed two traces that went down there that were soldered together, but didn't seem to run to a component). So, if you know your way around a soldering iron, and don't mind some frankenstein work, you may be able to solder wires to the pins the traces lead back to for the buttons, ir, and power led on the PCB (and send the wires to either another board, or your own external components), and saw off the bottom of the PCB so you wouldn't have to worry about it extending so far from the screen.
That's a lot of work though, and could easily end up with a dead board / monitor, so I wouldn't suggest doing that.