Dont forget. Everything doesnt need wired back to the battery as shown. Although it will need wired to a suitable 12v feed.

That can be at the battery, the starter, the alternator, or another chosen connection point that you create.

Items like coils, fuel pumps etc are sometimes better wired directly to the alternator, as that will be the main power source for everything when the engine is running.

Or if not directly to the alternator, directy to a connection point which has heavy gauge wire from the alternator.

I have a fusebox/loom/relay panel wired directly off the alternator via 16mm^2 welding cable, which in turn goes directly to the starter motor, which then has 35mm^2 welding cable to the battery at the rear. My fuel pumps are fed directly off this.

So in essence, whilst there is some length to it, the cable feeding my pumps is no less than 16mm^2 from the main power source ( alternator ) right up until it has to step down to accomodate fuses and relays.

Welding cable is ideal too as its very flexible, and has quite thick insulation. ALthough obvioiusly its only to provide suitable power takeoffs