[Al Skierkiewicz]

As a rule of thumb, #6 wire will drop 0.1 volt for every two feet of wire length at 100 amps. Stall current on a CIM motor is 133 amps. Four CIMs at near stall will drop roughly 0.4-0.5 volts every two feet. Remember that the black wire and red wire both carry that current and the total length is included in that calculation.
At 12 pounds, the battery is a good way to manipulate COG. I always recommend that teams keep the battery low, inside the robot, to help prevent tipping.
In the order of things, COG first, short wire runs second. Symmetry can be compensated in other ways. If you tip over or can't maneuver, having good electricals won't do any good.