Although not commonly adopted it is possible to loop the wire from a roof light bar.
How to wire roof rack lights.
Drilling through the roof and i stalling one of the bulkhead wiring connectors with a single loomed connector with all roof rack lighting so it can be quick disconnected at one central location and at each independent light woukd allow removal of rack without messing up wiring or looms or having to remove wiring and lights to remove the rack.
Follow along as i show you how i am going about wiring the lights on the roof rack of the zombie jeep.
The cabling is run along the length of the roof attached to the roof rack or rail and in the case of a ute will generally loop across to either the sports bar or headboard of the tray itself and head down to the chassis rail then off to the engine bay.