First, great idea.

My next thought is that you are going to need to check with various
"authorities" before moving too far forward. There may be some
stringent requirements when hanging a ~700lb (310kg) item over
people's head.

Start with the mall. They may point you to the professionals that
they use (and alluded to earlier). I will bet you will have to get a
sign off from a city/county/state official.

Keep us informed as to what you find out. I, for one, am very
interested.

- John