I used balsa wood to block block out the chest and hips. I missed taking a few photos but I also carved out a slot for the armature to sit inside the balsa wood.
I trimmed some soft foam to fit the tummy of the puppet.
Looking at some of the puppets the third years are making, I noticed they had added K&S rigging points to the ball and socket armature. I decided to use the existing rigging point in the hip of the armature rather than glue K&S to my puppet. I might add a K&S rigging point to the chest of the puppet because I get the feeling it will be top heavy and will need the extra support.