The issue i have with this, is that considering the very nature of Rollcage racing, tracks should be very open and unofficial in nature, rather than laid out racing tracks.
Another thing is that i dislike the idea of obvious shortcuts. Nobody would take the long route. I'd much prefer many various routes and diversions through out the track.
I think track designing for GRIP is a little more complex, as you're building around an environment, rather than having a simple closed circuit.
Not sure how you plan that out...