I'd say you probably want to trace out the track. Try setting up a script for the camera that adds the current position of the camera to a list every so many steps (AKA don't do it by time, but do it by distance.) Once you're done tracing the track you should probably dump a list of positions to a text file so that you can copy them and use them in-game.

The more positions (aka checkpoints) you have around your race track, the more exact the position bar will be.

Here's a picture for demonstration:

![race][1]

Sorry about the bad image quality. :P

Hope this helps!


  [1]: https://i.sstatic.net/RtbWT.jpg