Where I live a professional engineer is a legal title that can do anything. You are expected to know your limits, and as an engineer figure out what is right from textbook principals. I know their are professional engineers where I work, I keep thinking i should join them.

Can you send mains power over coax? By code no, but an engineer can do the calculations and sign off and it is legal. Of course if it isn't actually safe the professional engineer is also legally liable in court for deaths.