I wouldn't do an outlet for a client that comes from another junction box and is hot- that's illegal and my insurance wouldn't cover it, anyway. The inlet/outlet whip IS legal in Wisconsin and is seen as similar to an extension cord. Also, WI allows making repairs to electrical wiring if leaving it would pose a safety risk. I have had electricians (licensed and bonded) OK me terminating a box or dropping a whip for a TV when we have worked together in the past- they know I would never intentionally do it wrong because I know their profession is at stake and it might save them a trip just for one outlet. Pretty much a no-brainer if they would have to return for other work, anyway. I tag the work I did and they can check it next time they return.