Is your inverter a 24v? just checking after you wrote 150 Watt from a cigarette lighter socket (dunno if this applies to truck aswell or just car) and 300 watt for anything else
24v socket, at 15amp will give 360watts, I wouldn’t want to be pulling a constant 15amp draw, it could be getting a bit warm! especially if its a cigarette lighter type, hella types have two type of plugs the ones for higher current rating have earth contacts all the way round the plug rather than one single one.