That is such a practical way to train, especially since strict percentage charts can feel totally unrealistic on days when life stress or poor sleep catches up to you. Using RPE makes total sense because it adapts to how your body actually feels in real-time rather than locking you into a rigid number.
If you want to easily map that out and figure out your true working numbers without guessing, you can plug your numbers into an free online RPE Calculator to track your progress and adjust your lifting weights on the fly.