Do not attempt.
Find the stock body harnesses and then go through the wiring schematics and slowly start removing wiring systems you won't be using. For example, on my hatch, I have an S15 front so I eliminated all wiring that has to deal with the pop-ups. I also removed all A/C wiring since I never plan to have A/C.
If all you need is the basics, once you remove all the wiring systems you don't need you will be left with a lean version of OEM wiring. You will also find that by going through the schematics, you can re-purpose some circuits for other things.
Good luck, it's best to know someone who is into wiring who can help you along the way.
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