THE best way to do it...
Raise the front end of the car first. Place the saddle of the floor jack under the front crossmember and raise it. Place your jackstands either under the rockers or on the frame rails. Make sure your parking brake is set. THEN move to the back of the car. Place the saddle under the differential and raise the rear end. Place the stands in the appropriate places and you're all set to go to work! By the way, the tires are a great idea. I would think stacking them, two at the front and two at the rear would work perfectly in the event that the car loses balance and falls.