That's the same class mix I have. You are higher level than me, so I don't have specific advice for Maraudon or other dungeons.

But generally, I've levelled 2 groups in retail, my advice is to be really really open minded about changing your key maps and macros to help you handle new situations. I don't know how complex your bindings are already, but if you think frost nova will be a good strategy, move it to an easy keybind and just practice using it. Consider driving from the mage or the healer, instead of the tank. Consider making a 'panic' button (e.g. everyone does /follow on priest, eats a healthstone and priest casts prayer). Consider using ISBoxer menu/clickbar on screen for key maps that you always forget the binding of.

Also, remember that controlling 5 characters at once is never going to be as effective as 5 people controlling 5 characters, so there will be situations were you have to overcome a difficult challenge. And that is actually the joy in the multiboxing meta-game.