No UBEC or LVCs required, they are built into the escs. All you need to do is use a Y-splitter to join both escs to the receiver (throttle channel). Only important thing to remember is that both escs need to be pregrammed exactly the same, to prevent the motors fighting eachother as they spin. This should help:
I would also suggest using that parallel battery harness to ensure both batteries discharge evenly, and hit LVC together- you dont want one motor to stop working, as the tall gearing will quickly overload the other motor if it has to do all the work itself. Wait until the V-twin guys see this truck, they will soil themselves...