If you remaster a very large system using the --workdir option it will likely fail to create an ISO ...... but the necessary files will be in the --wordir and can be used by LiveUSB Creator to generate a LiveUSB install of the full system.
I did not know that. Can you give me more details. That sounds ideal for my purposes.
I don't know what details you need .... or even if there is any more to tell

Do a remaster as normal but add the extra option which should specify the full path to a directory you create for the purpose.
Make sure that wherever you create the workdir that there is plenty room ...... about twice the room that your install takes up should do.
I would also, at least initially, suggest you use the --gzip option, which although it creates a much larger install does so much faster. The size should not be much of a concern on the first try.
With the chosen extra option/s added to your normal mylicevd command, run it and wait until it finishes.
At the end it should tell you it failed to create the ISO.
You can then use the files in the livecd (I think) sub-directory of your 'workdir' from LiveUSB Creator to do a LiveUSB install.
If there is anything else you will need to ask a specific question .... I cannot think of anything else
mylivecd --gzip --workdir=/full-path-to-directory <rest of your command>I hope I got that correct

Try
mylivecd --helpin a Konsole to see all the options available.