Dude - you still have 4.5 hrs to go. Put on the headlamp and go for it! Just keep repeating: "one more wave" 14km. You can do it!
Sorry, had one logged at miles instead of km; now need 22 km. Getting further away!
You still have 4 hours. And a nice evening. What's the problem?
I think the best solution is to declare tomorrow more of the holiday and just add it in.