The reality of the offical map is that it was done by the D&R parks commision. They map the park from the Canal Rd lot to Middlebush. But since until recently they didn't really even understand what was going on east of S. Middlebush they did not map it.
I recently brought the Park's Naturalist a copy of the GPS mapping of the entire system. As expected budget concerns come up quickly.
The rt 27 side is ever changing and I would sumit that 1/2 the fun is getting to know the trails and exploing what it out there.
You can loog at fred's gps log and find a reasonable mapping.