Joining a NetApp to a domain on a Read Only Domain Controller

I have an isolated network, into which I've built a vfiler. The point of this network is that it's a non routed 'test' network.

However, there's a need for LDAP/Kerberos and CIFS access to the filer, via domain level accounts.

So we have Read Only domain controllers deployed.

To join a Windows box to the RODC, we would:

• create a machine account by hand.
• join the domain, and specify the machine account password on the client.

A spot of googling finds me: https://kb.netapp.com/support/index?page=content&id=1012918

Where the advice is: Point the filer at a writable DC manually first.

I'd rather not do that if I can avoid it – I don't have writable DCs on this piece of the network deliberately. More importantly – my vfilers are on an ipspace, so I can't even temporarily 'jump over' to a network with the right access. (Which is sort of the point I guess, but even so…)

Does anyone have a suggestion for how I can accomplish this – I'm assuming I may need to extract some information from my DC and transfer it over, such as a servicePrincipal. Or perhaps just 'set' my CIFS password manually somewhere.