> I don't understand why anyone would use passwordless disk encryption
You want to install and operate a device at a remote site with restricted (or no) VPN access and where you don't trust the local staff?
You want to install and operate a device at a remote site with restricted (or no) VPN access and where you don't trust the local staff?
There is precisely zero chance that the relevant IT security goons would allow any kind of remote KVM/LTE connection.
Any change the untrusted local staff could make to the server, they could also make to the KVM machine (e.g. turn it into a keylogger).
Now you have the same problem but with a smaller computer.
You cannot turn untrusted systems into trusted systems by adding more untrusted systems.