Right, and that's something that can't be done in the current standard. Hence this entire proposal has to wait until some major changes can be done.
Yup. And then those changes should not be a repurposing of an existing mechanism (element ranges on the string type) but something more appropriate for the goals.
In Python, it's done with a prefix - u"asdf" is a Unicode string, and b"asdf" is a byte string.
Since nominally strings are Unicode (with the extended ISO 10646 range) strings now, I think "asdf" can be left as the syntax for that, and we only need a new syntax for the byte string ("buffer") type. We can also look at Java, which has byte[] as the type for byte strings, requiring literals like {'a','s','d','f'}, but I would like to see something a bit more convenient to use. :-)