Wow, that's really horrible. I have a file sitting around with a couple of newlines in the name just so I can see how many programs don't cope with it, but I hadn't thought of using a lone combining diacritic.
If anyone wants a command to make one, try
touch $'\U035F'
(using U+035F COMBINING DOUBLE MACRON BELOW for no particular reason, see [1] for more)
[1]: https://en.wikipedia.org/wiki/Combining_Diacritical_Marks