Retro fitting tow bar to 2000 ML (chassis 163)

I have fitted an Oris swan neck to my ML. I have cut a neat hole in the pull-out in the bumper and all is fine. However I have two questions:
1) While I had the bumper off I noticed a Mercedes sticker saying that a number of parts needed fitting if a tow bar was to be retro-fitted. Given I have simply bolted the new swan neck to the chassis, what else do I need? This is only for a cycle rack and not for towing.
2) Electrics. Because I intend to fit a cycle rack I need to fit electrics. Anyone got any experience of fitting an electrics fit to an ML (single socket). Is it easy and reliable? Just wondered if there were any bad experiences for me to learn from!
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