I am working on a scheme to clone a production, domain-joined virtual machine, bring that machine up off the network in order to prepare it to be converted to a template.
One issue that comes to my mind is that I will have an issue removing it from the network as it won't be able to reach any domain controllers. Is there any way around this?
What problem are you experiencing? This should work fine.
Clone the server to an isolated network.
Remove the cloned server from the domain. You'll get an error that a domain controller cannot be contacted, but the cloned server will end up in a workgroup.
Sysprep it.
Convert to template.
A domain client doesn't need to be connected to the domain in order to disjoin it. The only caveat being that the computer account in the domain will be orphaned and you'll need to delete it manually.