We'll be giving this PCB a try this year. It's 2.5" X 2.5", has its own 5V, 3A buck regulator and also provides a mounting point and power for the Arduino Micro. The only control system connections are 2 digital inputs from our MXP board to select animation patterns.
Our testing has shown that this should be able to drive 3 meters of Neopixels all day, as long as we aren't blasting full-brightness white the whole time.
