Well I fitted the Redarc today no major problems, ran the extension wire inside the passenger side door sill. I installed the remote head just on the LHS of the lights switch/module, awkward to get to for someone like me with fat fingers but achievable. I mounted the controller just in front of the LHS taillights, wires supplied reached the positive on the battery (which was the farthest connection point). There was one minor problem, it was mentioned earlier in this discussion about the colours of the wires in the Holden loom, I found the plug but the two wires were blue and the other black/white tracer, according to an earlier post the black one was quoted as purple (Gottavecalaisv). The blue wire is definitely for the trailer brakes but the black one doesn't have 12v on it when the brake lights are on. It is only a fairly light wire, that would suggest it is for data(can bus), so does the Redarc accept Can-bus?
I have come to a halt, I will have to chase info tomorrow. The controller, the extension cable and the remote head are all installed, just waiting to find out about this wire before I connect and power it up.