I dont really see the double teaming as a problem, everytime my team is double teamed they completely give up. Two average people can stop 5-6 attackers. Most times im left defending by myself, which while effective, isnt a long term solution and I eventually get overran if the attackers timing is right. With one additional defender we would be able to stop a flank, just can't get a double-teamed team to provide that player most nights. You'll have 15 people fighting one team, and 1 fighting the other. When a team rolls over of course the other team is going to keep taking bases. The easiest way to get a team to stop attacking you is to stuff their attempt, and human nature will take over, they will go fight the other side.
My suggestions is to stop worrying about how many bases you have or how many teams are attacking you and put up a fight. The victim mentality is so bad lately that no one wants to fight another team if they have a chance of dieing.