Long strings can actualy use quite a lot of power when they are off (most of the time)
Any chance that you can add a setting to toggle a pin when the LED's are off so a mosfet could be added to disable power to the string?
e.g. https://raw.githubusercontent.com/DotNetDann/ESP8266-MQTT-JSON-SK6812RGBW-HomeAssistant/master/Wiring%20Diagram.png