Meet in two different groups, with one person in common. Take good notes so that one person can communicate what you decided/talked about to the next group. This can work until the "final" decision stage of what the focus of the paper will be and the final changes to the draft. For these, you'll need probably to meet at least once (for the decision making) or pass the draft around continuously until everyone is ready to sign off on it.
Back to I don't have time to meet out of class...