I've seen some similar installations for a commercial bakery and a small manufacturing plant. The Inspector insisted on boxes at the joist line, with a blank cover, and Kellems-grip cord connector out the side with 12/3 SO cord down to the twistlock cord connectors. They hung at about 7' above the floor so most people and fork lifts could get by without hitting them. Would be worth looking into, and checking with the local AHJ to be sure before installing.
