To avoid disabling SIP, you can create a bootable drive with CampTune installed, and perform redistribution of free space on the system HD booting from this media.
If you start CampTune on a computer with enabled SIP, this message will appear:
To launch Create Bootable Media wizard, press Create Boot Media and choose an external disk for this purpose.
You’ll be give an opportunity to back up the data located on the external disk. Select Save Data to save the data, or Erase to destroy it.
Wait, until the process of creating recovery media is completed.
Once this operation is successfully completed, a dialog box suggesting you to boot from the created media will be displayed.
Click Restart now to boot from the created Recovery Media. If you don’t want to restart now, then click Don’t restart.
You can start up from the created boot media later. For this purpose, reboot your computer pressing and holding the Option key immediately, so that the Startup Manager opens. See this article for details.
Select the required bootable partition and wait until it loads. Then launch CamptuneX.app and perform the required redistribution of free space on the HD.
Note: CampTune recovery creation will fail in case of broken Recovery HD. If Recovery HD is damaged, Internet Recovery will start upon boot from Recovery HD, which is totally safe and won’t affect your installed OS X. Just make sure your Mac is connected to Internet using wired connection. Boot from Recovery HD again after Internet Recovery process is completed.