Sparky,
Are you an electrician? Just asking, most people with a sparky handle deal with electrons.

What you need to do is remove the red wire from the connector that goes to the RX, from the ESC, this disables the 4.8V to power the RX. Then use the 4.8v pack to power the rx by using another available channel on the RX for power.

This saves all the lipo power for the motor. Most people use this set-up flying the larger electric planes.