FileVault 2 authrestart from NetBoot


Is it at all possible to get fdesetup authrestart to work when rebooting to a FileVault 2 encrypted device from a NetBoot volume? For instance I just reimaged a Sierra machine with a Casper Imaging NetBoot. Since it was a reimage I didn't turn off encryption, I just mounted the encrypted volume and installed some packages. If I check the "Boot to target drive after imaging" it just boots back into the NetBoot. fdesetup authrestart tells me that FileVault is not enabled (because it's not on the NetBoot volume) and fdesetup authrestart -device /Volumes/Macintosh HD tells me that "The -device option is not allowed for this operation."
Is this just not possible?