The map for this year's route is available on Saratoga Spa State Park's Facebook account:
|Five Mile Trail|
So, I think this draws the mystery to a close. The Five Mile Trail was created for this race, and after reviewing other posts on the park's Facebook page, it looks like the route has changed over the years, which explains why the are legacy markers scattered here and there.
There's a certain temptation for me to enter the race this Sunday: I really enjoy this trail, and it would be fun to run it in a race setting. Hopefully I'll be fully operational next year.