Sorry for the late response.
I had to do this about two years ago for our city's Solid Waste department. We didn't have the VRP solver at the time... so I had to do most of the planning outside of Network Analysis. Organized the city into geographic polygons with a min / max pick up of about 280 to 300 collections. Then I ran the standard route solver to figure out best pick up order, by travel time. I had to do some tweaking in the final stage of development to organize the actual driver’s routes, but it worked. Our city is about 90,000 in its population base…
Hope this approach helped