Extension Cords - Electrical Hazards & Safety
This is really a subjective question, and there's a lot of slop in the definition of "temporary". 

If you know you'll use this space for the long term as it is, I'd work on getting some hard outlets installed. If not, I'd get a 2" hole saw and cut some pass-through ports at strategic places out of sight between cabinet sections and through the floor, as needed.