Yes, a .iso Live Image can be customised with the install/removal of programs
and changes to settings.
https://trisquel.info/en/wiki/customizing-trisquel-iso ( some steps are
optional )
and then that custom .iso image can be burnt to CD to make a liveCD or copied
to USB to make a liveUSB.
https://trisquel.info/en/wiki/how-create-liveusb
( * Data safety tip: double check the output-file if using dd to copy the iso
, to make sure it is the correct USB media )
-/-
A simpler approach to the above is to install/customise as regular to HD,
then backup the HD for use as a vanilla master image used to restore the box
periodically.
Clonezilla Live is one imaging tool that can backup/restore the image of the
HD.
https://en.wikipedia.org/wiki/Clonezilla#Clonezilla_Live
