I've updated to El Capitan and the issue was back again. So I did the trick with -DisableSleepProxyClient and it's working. I mean it doesn't wake up every two hours now. The only difference was, that I had to reboot to rescue mode, perform "csrutil disable", boot normally, do the trick, reboot to rescue mode, perform "csrutil enable" and reboot.
Do you mean that after you apply the RTC patch, you re-enalbe SIP?