This took under 2 hours on foot. Cargressers will need to walk. It keeps you away from most of the busiest roads, and later missions may have you hack portals done earlier to helpfully steer you on your way for the next leg. A decent mission. Reasonably sure it could be 24/7 but lighting in some areas could pose a problem at night.
A couple steep gradients on the paths and a couple portals that you may struggle to reach from the path in the park may mean going into grass.