Wow, ive never considered this setup as multiboxed in the arena.....
Single target is the way to go...SWP and mages shooting...
If/when 3 or more are clumped together, go for AoE...
Your biggest concern will be fear, so try to kill/silence/sheep the aoe fearers they have..

To tell you the truth, i think it will be hectic as hell :P
Not that i condem your effort, but it will be hard as hell to win with that setup as a multiboxer.
If you should succed on the otherhand, /respect

GL, and keep us updated on your results might be an option for other PvE groups here