Received my pads yesterday. Thought I may as well fit them because I new I'd have to remove the seats to get the tunnel off to renew the rotoflex coupling, will do the webbing at the same time.
A quick check of the wiring diagram shows the switched feeds are white and green or white on my car so will use one of those to control a relay with power coming from a suitable supply, maybe the 50a circuit to a new auxy fuse box.