You just made me think of something, I wonder if the separate hardener from Kodak Rapid Fixer can be used just as a hardener in the situation you mentioned? I have several of those small bottles which I have no use for. I do use brown toner regularly but I never bothered to use a hardener after.
Greg Davis helpfully explored just this issue: (there was a url link here which no longer exists)
I've started buying the Kodak Rapid Fixer again as a result.
