Suggestions on how to setup new team with existing characters on main account

I just started multiboxing again after soloing since the launch of classic so I already have 1 account with a bunch of medium level characters and I'm not sure on the best way to integrate them (if at all) with my multibox.

I was planning on running Priest+4 Mages for my main comp but my original account already has a 43 Priest, 31 Mage, and 32 Warlock.

I figure my options are something like:

• Make a brand new PMMMM team and ignore existing mage or swap it out when others catch up (kind of a waste but existing mage isnt that geared or anything)
• Go Warrior+Priest+Mage+Mage+Mage until 31 then swap out the Warrior for existing mage (probably safest since tank might work better for later content)
• Level squad of 4 until 31 (probably screwing myself out of being able to solo dungeon grind)
• Somehow use either my existing Priest or Mage with 4 others without screwing over their levelling speed (healing out of party? wouldnt work in dungeons though)

Any suggestions would be appreciated because it is going to take me hours to configure ISBoxer and I have limited character slots left on 1 account so I really want to get it right. My 43 Priest is probably the one id like to keep the most but I don't think it brings enough damage or utility to make up for the XP losses id get from using it with 4 new mages. I assume shield tanking with my priest+4 mages doing damage would be abysmal XP since id still have to stick to content around the mage level.