For younger eople you could add a white jersey for the overall time.I think this should be for people under 20 because some people might not have a chance to fight for jerseys.
But there is already a white jersey for 100km. You would need to male it a different color/pattern…
I have just done a 200km session (just over 7 hours) and there was not special jersey for the challenge but I new that anyway.
However, I thought that this could be something to be introduced as a new challenge to get a jersey of sorts.