It's quite disappointing that the TomTom does not have that feature, and even more that they don't plan to include it (as far as I know)
However you can use Locus Maps app (android), with free maps from openandromaps (Open street maps based). Locus will try to guide you while on a track regardless whether routes exist or not. It will look for sharp turns or similar features and point that to you. It also has a feature that if you deviates from the track, it shows how far (straight line) are you from it. You can also rejoin the track at any point and it will pick up from there. Great app with lots of features. I use both the TomTom and Locus depending on the situation.