Since IPA uses a lot of unicode characters, would it be that much of a problem? IPA, imo, usually has a very specific look to it that wouldn't be confused with "normal" text.
Most of the time, italics aren't actually all that important though, and could easily be replaced with other linguistic features.
Edit, another thing is that the slashes is actually graphemic notation, not phonetic. There's no reason that you have to use something modeled off the IPA there, it's just common to do so. You could use any alphabet.