Get lots of rubbermaid containers. I had my old tank set up and needed to empty it first as I was putting the new tank in the same spot. I set up the rubbermaids with heaters and powerheads. And I transferred as much water out as I could first, then I took out the rock and put it in another container. I saved almost all of my water as I went from a 72 gal to a 120 gal. So I needed to keep most of it. A little different in your case. Put your corals in one container, fish in another and rock in another. I would not use the water from the coral one however.
It takes longer than you think. I would take the water out the night before...if possible. As Naesco said and let the fish calm down overnight.
But I would say you should keep the rock in water while it is being moved and get someone to help.
Hope this helps if you have any questions either Email or PM me.
Leah