Re: Ouch
We've gone further and air-gapped our test lab. when we need to move a machine from the lab to production (or vice-versa) we clone it to a small NAS appliance (think a Synology or QNAP 4 bay device), and hand-carry the data to where it's going.
It largely works, although we do have some vendors that are cranky about how they get remote access to the lab. (it's via a IP KVM unit and a handful of desktops cabled up to it; the KVM is on the production network, the desktops are on the lab network.)