All of / on my main machine will go easily onto even a modest thumb drive -- "df -h /" says only 11 GB; meseems I've heard of other people keeping back-ups on thumb drives.
But what about the OS? If I were to put, say, the current release of Fedora onto the same stick, would I be able to use that, while visiting in-laws for instance, as if it were a live CD =with= all my data?