When I purchased the Simkits panel, it came with a rather crudley, slapped together, MDF ‘pedestal’ covered with a replacement C172 pedestal ‘outer shell’ made from plastic. .
I set about making a new pedestal structure. I purchased two 6mm sheets of plywood, drew the shape of the pedestal to match the plastic shell. I then clamped the two sheets of wood together and set about cutting the shape out with a jigsaw.