Note: I don’t maintain Whonix KVM but I can answer a few build script specific questions.
The usual build documentation:
--flavor whonix-gateway-cli
--flavor whonix-workstation-cli
Might be Undocumented, Untested or Unsupported Features?
--vmsize 200G
as per:
Seems undocumented. This page is at time of writing for VirtualBox only.
Mostly unspecific to Whonix. Hence:
Never tried. Never heard. I suggest to make this a question unspecific to Whonix or just try.
You could contribute to this one:
Generic Bug Reproduction / research / contact upstream / enhance documentation.