First off you would need to install a power inverter,
now I hope you don't have a sub in the trunk, becaus eI would think a pc would be like an amp Vibration not a good Idea.
Other than that sounds like an Idea,
I would say a laptop with a 2 monitor out put (s cable) and mount it in your glove box use the monitor output and run it to a few LCD screens. get a removable hard drive and mount under the passanger seat for you music. Make sure your head unit has RCA inputs.
I sure I could think of some other things that will be needed
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