I would just go ahead and wire from the toggle into the harness and use it, it's there for a reason, just follow kinda factory wiring diagram just use your toggle switch instead of factory and it should be kinda close, without a relay in the underhood fuse box of course though, just skip it and run power from switch to hot for lights(thru harness) and it should work I'd think, atleast give it a shot and if not try something else