Several years ago, I experimented with various toners on Ilford Warmtone RC paper. In addition to very extended periods in various solutions and washes, I have had this paper in hot tea and heated Nelson's Gold toner for up to 20 minutes. I don't remember the temperatures involved but they were pretty darn hot. This was a real torture test for RC paper and, yet, the paper looked great and held up to such abuse with no ill effects. I can't say how other RC papers may respond to this extended wet time and high temperatures but the Ilford Warmtone did fine.