There's also a python script you could check out called P3D Solidify that mimics a 'shell' type of modifier.
https://www.highend3d.com/maya/downlo...dify-5727.html
Here's a screencast on using it (one of his examples resembles what you're trying to do).
https://www.screencast.com/t/K2CCAbwyiUX
It's also pretty cool for simulating something like Max' inset.
"Terminat Bora Diem, Terminal Auctor opus."