Probably would still take a significant amount of programming to make a course persistent.
On that note, I wonder if PG's could be used, somehow, to help with that?
I mean, even if we assume the code for demarking a race-course was pretty efficient, when you'd got 100,000 players all creating them (and, let's face it, it's inevitable that people are gonna create circuits to SagA and back, to Beagle Point or just right around the galaxy) it's probably going to add to the server load.
And then there's issues with people flying around and constantly seeing race-markers - and the markers, themselves, being abused for doing stuff like, say, marking VO's in a ring.
Perhaps those issues could be mitigated by storing the course data on a client-machine as some kind of plan-file which you could load/save to generate the course and then racers would have to join your PG to see the course?
That'd, hopefully, minimise the server load and it'd ensure that people who didn't want to see race-markers plastered all over the galaxy wouldn't see them if they weren't in the PG.