There is another ever simpler way to Join the Dark Side
Go to C\Program Files\Ubisoft\GWX\Data\Cfg and open the GamePlaySettings.cfg file. In there towards the bottom you will find the [RealismPercentage]. This is an indication of how the different realism settings affect your renown. Set the ones you don't use to zero and make sure all the settings add up to 100%. Next time you go to play the game you can "cheat" it to make it think that you're playing in high realism settings. That way you will be getting full renown. Make sure you actually play in 99% realism and not 100% as then you cannot exit the mission (you have to dock manually).
Good Luck
