I would suggest work out how many circuits you want to wire, and from what you are saying it is around 4 to 6, so a generic aftermarket harness such as a painless 6 circuit would be the go.
Or, work out what you want, draw up a diagram, get some rolls of 10 and 20 amp wires in different colours and away you go, but look at things like the actual lights you need. I will be using cheap china ebay led lights that draw no current, but are the same "spec" as standard to meet the rules, but no relays needed due to low current. Also look at for lights wiring them in series and run the circuit like this:
Power > Switch > Light one > Light two > earth.
Only downside is current draw will be the addition of all the globes, but with cheapy led lights shouldn't be an issue.
I would also suggest circuit breakers over fuses, if mounted on an easy reach panel, if one trips then just push it to reset and continue on and then look at the circuit later.