In my writings, I would like to indicate short and long vowels when ambiguities might arise (mainly between nominative/ablative and vocative/adverb). Is there a common/attested way of doing this without having to mark every single long syllable with a macron? I have seen people using â, à, etc. for some words, but I am looking for more systematic rules (which words and which diacritics).
Maybe marking where the accent falls is a better option?