I can make you up one and send it your way... 2-3 days shipping, 1 day processing to make the harness. $85 plus shipping (about $10)
Can't do it for free, the materials along cost about $60. $25 for an hour of my time.
You should put this on your web-site as an option. If I elected to buy the reverse lights (still thinking), I would go for a custom harness. Could do it myself, but not something I like doing. Bet there are others in the same boat.