I have had clients that ran huge grow ops in Bell Air and would run 10 gauge extension cords throughout - I think the lights only pulled like 1200 watts or something each.

I did a couple tours through some of these mansions and I still can't believe or understand how they would get away with gutting these multi million dollar homes. Rent was 25k-30k on some of these homes and they didn't even hire an electrician to wire things...  people amaze me.

Long story short, heavy duty extension cords do work. Probably not the smartest thing to do, but I had these clients for about 8 years doing their financials and they didn't burn down a single house. Luckily.