"I'm really glad you wrote it up (and happier with one post, frankly, although it did take me a couple of walks to finish reading). For what it's worth, I don't think you can do this in packer on Hyper-V right now, because the Hyper-V provider for packer is a(n) MSOpenTech thing which is basically at proof-of-concept stage (and written in go, so I just don't have the energy to try and fix things in it). However, if you can do it in packer on VirtualBox and then get it working in Hyper-V by "just" moving the drive image over, it's probably worth using packer just because "next time" you need it, packer will probably work for all of them ;-)" - Joel Bennett