Right - everything is grounded at the batteries. However I'd run a dedicated line from the negative on the battery to the mounting bolts on the tower. Then the whole tower would be grounded negative and I'd just tie directly into it for the negative on the lights. I've avoided adding anything else to my negative block under the dash besides a single line for LEDs - don't want to overload it.

I have no lights on my tower at the moment. I'll be running 2 forward spotlights, 2 rear spot lights, my anchor light and a downfiring LED bar. The spotlights will probably not get a heck of a lot of use but the LED bar and anchor light (most likely LED) will, hopefully anyway!

Part of my reasoning for this is to get away with a simple 4-wire loom going through the tube to the light bar: 1- fwd spots, 1- rear spots, 1- anchor light, 1- leds. If they are all grounded to the tower itself up high then I can avoid needing a 5th grounding wire.

I am running massive 0/1 wire both +/- for my amps to Kicker distribution blocks - not going to mess with that. This would be independent of everything else.