Last night I had the idea of reducing the weight of the platform by substituting the circle plywood platform with 2"x2" crosspieces on which a wire circle could be attached.
Two 8' length 2x2s would be attached (screws?) to the center structure going front to back and then 2 would be attached in the opposite direction, side to side. The material for the circle would be attached to the ends of the 2x2s curving between them to form the circle.
Currently there are 2 options for the circle, 12 gauge wire or 1/2 Plex pipe. PVC pipe has been suggested but I'm not sure it can be in a circle without heating it which would be a longer process. It might work since the circle is large, 9', the bottom hoop might not have to be perfectly round...hmmm.
The idea is something like this photo of another production of Nutcracker, less circus like though.