LED light bars take a fair amount of current, though you can't rely on the exorbitant claimed for wattage on-line. My 54" Nilight Light bar claims 312 watts, (
LED bar ). I measured it at about 225 watts drawing 16.4 amps.
I installed a True isolator and aux battery. Like most, I run the winch and all the accessories off the aux. I split my additional fuse block into "key-on" and "always on", that way some of the lower draw lighting, such as the pods and rear lights that only pull about 1 amp each, can be used without running the engine.
The True also allows the main battery, and it's charging system, to help with heavy loads on the aux battery. Winching can draw well over 150 amps (one spec for a 4,500 lb winch says 178 amps at full load), so the fact that the True can pass up to 140 amps to the AUX battery means it can help out, but only when the engine is running - (it needs to be running as the main battery must be above about 13.3 volts before the True will start charging the aux battery). Okay, too much detail, but you are on the right track!