You can do this by just implementing From<u8> and Into<u8> for your type - using the enum representation only for assignment or pattern matching. The more principled solution AIUI would be to have "patterns" as a first-class citizen within the language.

Storing the tag 'out of band' is something you can only do as part of some larger object, in which case you can similarly have getters and setters that take or return enums and do the appropriate conversion.