I have my USB stick setup using Easy2Boot. It allows me to drop ISO files onto the USB drive and boot from there no config or tweaking needed.
I have been doing research on making it persistent. I have found that you can use a file or a partition called casper-rw.
It has info on how to use the file, but my question is. Can you have the casper-rw file directly in the root of the bootable ISO or does it need to go into a special folder on the ISO? For that matter can I even have the file in the ISO or do I need to have it directly on the USB drive?