ScottyWarpNine
Mostly Harmless
It's up to you. The harness would actually reduce the wires being routed through your wing tubes, and the pig-tail design is intentionally there so only the extension is routed, then the short harness is plugged in at the end, joining everything up. Everything still remains perfectly modular.
In this particular case, since you've also got retracts in the wings, you'd need to add on another row of pins and another wire to match . . . or build the whole extension out of a four conductor strip of ribbon cable, and provide servo power locally from the ESC
A distributed harness would work best with a small bay at the Nacelle for everything to join at. If you've built one to house the ESC behind the motor, that starts making more sense. Otherwise you get to feed servo extensions and power cables into your wing tube (granted you've got a bigger than average wing tube). Three extension runs + power cables isn't unreasonable, but you've got other options.
I'm not sure I follow 100%. Are you saying the aileron servo and gear servo would be powered locally by that wing's ESC's BEC, and just the signal and power wires are fed back throught the wing tube to the receiver? Then the receiver itself and the tail servos would be powered by my external BEC?