In 4th the Rigger Cocoon has a Structure Rating inbetween Reinforced and Structural and an Armor Rating inbetween Heavy Structural and Armored/Reinforced. If you take that as a baseline and adapt it to 5th, you'll get 9 Structure and 22 Armor, instead of the 10/20 it has in 4th. So you might as well just stick to 10/20.