I finally did it! No City official could tell me the distance of the full course around the park. So I took a measuring stick and measured both the trail and "track" at Van Nuys/Sherman Oaks Park.
Here are the results:
The Trail (the large one that covers the park)
One Loops = 6888 ft (about 1.3 miles)
The Track (near Hazeltine Parking lot, circle 4 baseball diamonds)
2600 ft (40 ft. shy of 1/2 mile)
What's additionally rad about this?
1 Trail Loop (1.3.) + 1 Trail Loop (1.3) + 1 Track Loop = 5K (3.1 miles)
For a 10K, just double all of it.
View a Google Map of Van Nuys/Sherman Oaks Park