I don't think there is any problem with the length of your full name as a display name. Actually I quite like it...
If you want to be addressed using a nickname, you could put that into your signature...
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus