SamyGO

Can i autostart a virtual usb device?
Get the PVR to use it ?
Even from standby for a scheduled recording?
What happens when the SMB Share that the virtual usb device is using runs out of space?

you can`t use SamyGO for sheduled recordings.

So after reading some other threads and your answer:

Can i autostart a virtual usb device? <- Yes
Get the PVR to use it ? <- Yes, but needs to be NFS
Even from standby for a scheduled recording? <- No, samygo doesn't start. But schedule turning on of TV before recording than it's possible.
What happens when the [s]SMB[/s] NFS Share that the virtual usb device is using runs out of space?

Nothing happens, recording stops...

Yah, this way is a bit complicated, but yes, it works

That's an interesting option and might also circumvent some cases where the TV doesn't recognize a CAM when recording in standby.
Thanks a lot.