USB Remasterig Using Minimum Real Estate

[utu]

Progress so far:

doremaster cloop image creates a fatter KNOPPIX compressed file.
doremaster create knoppix-data.img <anything> doesn't work.
doremaster prune knoppix-data doesn't work, with or without
a persistent store.

target LiveUSB still boots, but doesn't appear to benefit from
its larger size.

doremaster create knoppix-data.img <...> does not recognize an input
such as 2000 or 2000 Mb or <2000> or <2000 Mb>.