I find it hard to believe that a single LED is 3w. Whatever. Since you are going down the road of "Possible Zero Power" you may need to add a gauge to help you out.
I am converting a simple box cargo trailer to a Toy Hauler-Camper trailer. I added LED lights, 120v Converter (120v >>12v), 600w 12v Inverter (12v>>120v), outlets for Alpicool Fridge (Extreme low power use, like 5-6w/hr) other 12v outlets, 120v TV/DVD player, pump for H20 shower, and so on. I am making the whole thing operate with 2 batteries (120amp +100amp) and 2 zoomie 100w solar panels. I want to go places, do things, etc OFF-Grid. The entire system is independent from tow truck. It is important to know what is in the batteries.
Perhaps look at "150A High Precision Watt Meter and Power Analayzer". I don't remember where I got it, Amazon maybe. It operates at 8-60v.
It reads: A - what is running now, V - battery voltage now, Ah - what is being used, and W-what is running.
It cost about $15 IIRC. Simple to add, connects to -/grnd and +/from supply, anywhere after the battery. It is sensitive enough to detect if I turn on 1 more LED light, or even turn on digital temperature display meter.
I have tested LED lights and found similar very low "actual current draw", but it still adds up. If your new LightBar is a power hog, ditch it.
Rely on jump or power pack or battery tender is too "iffy" IMO. A best solution would be to actually know what things eat battery/alternator power and what to do about it. Since you want to add something, maybe a "power hog" is just too much. BTW, I do not know if CFMoto ATV/UTVs can take a "jump start" without having something like a power surge protection on battery, unknown, IMO avoid it and the risk to on-board computers.
FWIW, I also put in a microwave in my trailer. I only plug it in to (in-coming) shore power, never the inverter, and never without shore power. It is nice to have microwave, but OK if not available. After all, camping and such isn't about speed cooking.
Just my thoughts.
YMMV