Anywhere that is a "blank" area on the map you can basically invent a location (you don't have to formally create a location to do this). Other than that, Frozen Ground comes to mind, but there are probably plenty others.
Can I still reference locations that aren't part of the canon?
the staff team luvs u
Yes! Map discovery isn't required to reference areas in Canis, it's just a fun way to let players add their creative additions to the map.