[jTheUmp]

Originally Posted by NFL Rulebook

Article 3:
During a punt, a field goal attempt, or a Try Kick, a Team B player, who is within one yard of the line of scrimmage at the snap, must have his entire body outside the snapper’s shoulder pads

Note: This restriction does not apply if a team does not present an apparent punt, field goal, or Try Kick formation, or if, after the offensive team has assumed a set position, there is a shift, or a player goes in motion.

Penalty: For illegal formation by the defense: Loss of five yards
from the previous spot.

So, there you go... if they line up in an 'unbalanced formation' as you suggest, the restriction is not in effect.