Yeah, I'm not sure / confident about the whole backup & restore of the channel states and all, though..
There's a great entry in the documentation about
various backup practices. You will probably end up using the
backup plugin with a remote directory or some removable drive.
I would just get the new drive, close my channels and reinstall
You could simply copy your hsm_secret and lightningd.sqlite3 files to your new node. This way, you wouldn't have to close your channels. Just make sure to copy lightnind.sqlite3 while your node is not running and don't turn it on afterwards.