The GOP oppo to STV seems notably insincere. Many places I've lived, it's really more likely to find Republicans who want to vote a straight ticket, and view "Republican" as an all-embracing brand. Whereas I've known many Democrats in the Plains who were more independent and more liable to vote for a moderate Republican who happens to be the more competent candidate for a given district or state. Chuck Hagel as Nebraska senator, for example. The GOP feigning of some principled stand on behalf of thorough study of the ballot is pretty transparent. If they made a genuine argument for that principle, and ensured all voters had adequate time and hygienic conditions to study the ballot, I could at least respect that as worthy of public discussion.
The best option, when someone gets to a choice of, say, Public Utility Commission candidates, and hasn't read their positions, is probably Leave Blank.