I'm not seeing the need for BOUT on the controller. The first pixel in a 2813/2818 string will ignore BIN if its receiving DIN. I believe these strings will work just fine with 3 wire from controller and 4 wire along the string.Not sure what BOUT is. this is what i found on another site on these nodes.....
BOUT = Backup Data Out. Its the outgoing connection from an upstream pixel that feeds the BIN or Backup Data In of the downstream pixel. If we are talking about modifying the controller firmware to change the existing CLK output pin to support a Backup Data line then it would effectively become a BOUT pin. The Backup Data stream is not an exact duplicate of the primary Data stream. It is shifted by 24 bits.
However, as I mentioned before, the first pixel in a string should not need a Backup Data In connection from the controller. The Backup Data is used by a downstream pixel when its upstream pixel stops sending Data Out.
I don't have any of these to confirm, but I highly suspect that the first pixel in the string (the one connected to the controller) only needs a typical 2811-style Data In. The controller does not need to know anything different and drive that port the same as any other 2811 string. Backup Data starts at the output side of the first pixel and gets cascaded down the string.