You don't need two tanks, the most obvious way would be to have whoever have the highest aggro (highest dps?) on the adds move to kite it. When you do contents with nonstandard party composition you need to adjust accordingly.
Oh and you can kill yourself by stepping into the middle circle, it'll kill you even at lv 60.
Edit: If you queue via DF you'll be synced to 50, and if you can't clear it unsynced I really doubt you'll be able to clear it synced.
