So matching a literal space will require something like /\ /? (Supposing I don't want to match a tab or a newline character, and don't want to match a character class.)

That's rare enough, I can't see where it would be a burden on me. Might be tough to read, though, which makes the character class a better solution. Or a quick comment, which is probably the best solution.

if ($string =~ /\ # literal space here
/) {
    # do this or that
}
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