Here’s the overview and the Carver MTB component:
Here’s the section from the NE end of Battle Creek (technically NE end is not in park, it's Scenic Overlook)
The area circled in red is where I’d prefer to jump out of BC onto the paved trail. This is at the base of Goat Trail (not a beginner trail!), from the satellite map close up it looks like one could descend a grassy area to the paved trails (see footnote ). The map below is from mtbproject (REI).
This would be a solid day of road/single track riding for most of us!
Update 6/9/2019 - more detailed version for a Sunday Ride
Depending on our timing a few segments can be dropped. There aren't a lot of places to stop and eat until the end of the trail. This ended up being a bit over 30 miles but it felt like 50-60 riding my mountain bike, doing the trails, and a surprising amount of up and down.
Segment 1: Groveland Tap to Overlook 8 miles
When we actually rode this (Strava, below) we missed turning left on Upper Afton Road so instead of taking Battle Creek Road to the trails we followed Creek back to Luge Connector. (Battle Creek goes underground again at the end of the park to pass beneath rail and freeway.)