Add an option of creating a virtual route for the challenge, or use "my route", and show the current position on the map (like the Flybys). It would be freaking great!
I made a challenge with my friends to cross my country (Brazil) in 2023 (3660 km). I'm using the group challenge to register the distances, but the map i'm doing by hand. Its very cool see where we are, but It's a little painfull make this all the time.