I'm putting a new fish finder thingy in too. Cables for that are like 30 foot long. What to do with the excess? Previous owner had them all jammed up behind the shifter/throttle housing. Aside from the mess, would that create an inductance issue?
Loop them in as large of a loop as you can for the space provided. A small loop can create a magnetic field and cause issues. Now with that in mind, I haven't had any issues with at least a one foot loop. You can even run them back and forth to take up the slack if you want.