Camera rig rail in sequencer - Major keyframe issue

After building a camera rig rail in the viewport, I am using it in sequencer to keyframe the ‘position on rail’.

The problem is that after adding many keyframes, when I change the length of rail in the viewport, all the keyframe timings for ‘pos on rail’ are getting messed up. Because ‘pos on rail’ uses a percentage based value (between 0 and 1).

Does anyone know a workaround to this? Or to somehow freeze the existing keyframes in a way, or make them distance based rather than 0-1?

Thank you very much!!