First, always use fuses.
second, always use relays.
third, always use the appropriate gauge wire.
optional- switches, split wire loom, indicator lights, cable ties, wire connectors, etc.
If your headlight switch works, it can do all the work, if you want all lights on at once. There is not any reason to attach anything to the Ignition switch, its already done for you. (wire to your headlights)
To simplify, mount relays run a heavy wire to your lights to the relay then to the fuse then to batt. Follow the diagram on the relay, goes to the two switch lugs. Now a trigger wire, light gauge is all that is needed, 14ga-16ga, as it will carry only a low amount of milliamps. splice into the headlight wire and run to the coil side of the relay. if you want a switch put it in this line, a dash indicator light can be add to the out side of the switch if wanted. now from the other coil side of the relay to a GOOD ground.
From here you could do many options, multiple relays (a good idea) multiple switches to split the separate relays into light groups. also splits the load up.
Doing it this way, keeps the heavy load carrying wire to a min. length so its more efficient. keeps you from messing with the Ign. circuit to stop reliability issues. its also the way the auto makers do it. they just use a dash switch as the trigger wire, which you could do as well. but my way, you kill the tractor, turn the Ign switch off it also kills all the lights to save your Batt. an over ride switch can be added easily.
many many options can be done. Have specific questions or options, I'd be happy to help out. Yes, I was a licensed master electrician.
This is not the only way, its my way to keep the circuits efficient and safe. while keeping the reliability of the tractor. Yes, 12 volts DC can make a big fire! do it safe if you do it.
Post here or PM me.