Cool website and thanks for the link!
I don't know the answer to your question, but wanted to point out that this is for a 'motorized version of the Pacific Crest Trail' and NOT the actual Pacific Crest Trail used by hikers.
FWIW, my buddy's were riding near the 'real' PCT. They came upon an unmarked intersection and took the trail. Lo and behold, they were on the 'real' PCT and came across a ranger coming the other way. Tickets were given all the way around. Apparently the rider is reponsible for knowing whether an unmarked intersection with a legal OHV trail is for a hiking only trail.
My friends ended up plea bargaining and getting a slap on the wrist, but the maximum penalties for riding on illegal portions of the 'real' PCT are VERY steep (if I remember correctly it was up to $5,000 and possible jail time).