The ESC signal wires carry the PWM signals to the ESC and they can be fairly long. I’ve run as long as 3 feet without problems. The only issue I can see with a long cable is the possibility of affecting the shape of the pulses. Check to see if anyone makes a repeater for long servo cables. This will boost the signal strength. It also won’t hurt to splice in some heavier wire, ie, at least 22 gage. Another source of info is the ESC manufacturers and they should know the acceptable lengths of servo wires.
For the power wires carrying the battery current to the motors, make the wire gage as large as possible to reduce voltage drops at the ESC. You don’t say how much current the motors take, but for a 40 amp ESC I prefer 10-12 gage if going more than a foot.