Just an idea when and if you do this you might reverse the polarity on the rear motors this would give you your back motors in the same direction and would not have to worry about changing to much as far as electronics and still hook up to the motor control board the same way, reverse the motor on the rear what would be black is now red on the motors. The I see thing is the current would divide between the 2 motor control boards from the single control board, that is if the 2 sides were equal in resistance. this would lower your current to the motor control boards and I think would slow down the motors and would not have any torque. AN easy way to find this out is where the motor control board plugs into the control board measure the resistance if the 2 boards are the same you should have no problem, can be different but would be better if the same ( difference would maybe 1 board measures 5K ohms and the other board is 7K ohms) . In a parallel circuit the voltage stays the same and the current is split between the sides (the split) of 2 motor drive boards. Think of it this way a river that is flowing when comes to a split in the main, the water is divided between the 2 rivers now (this would be your electrical current) but the force driving the 2 rivers does not change the speed of the 2 waters they they are the same (this would be your voltage). hey electronics 101. Now why the need for the same resistance on both sides, gets complicated, but if the 2 sides where not he same one side would try to draw more current but would not be able too and could end in damaging the control board because it would be trying to drive both sides equally. Again think of it this way, one side of the 2 rivers has a slight up grade the water is still coming at the same speed (voltage) but the water wants to back up to the main river and the slightly lower side (this would be your current) but cannot not do so because the main river is stronger ( from the control board main) and makes the the split still occur, at some point the river will break down if the balance is not kept the same. Any body can correct me if I am wrong but I was trying to explain some electronics and what to watch out for.