If you're removing the power adapter from the setup, your required cable length may change. Measure how far you need the power cable to run. When I did this, I added an outdoor USB outlet near where the camera would (re)mount, so I chose to make the cable significantly shorter.

Measure the camera USB cable (from the camera, not the USB) to your desired length. Give yourself a few extra inches in chase you cut the wires while striping.