FYI, you can use maps that don't connect to each other while you wait for the other ones to be updated.
While it's not ideal, if you avoid the areas where the roads end (and you don't get a CTD in general), you can still do deliveries in the areas the maps cover. The game will find an optimal route that automatically avoids the broken roads. I have Discover Ontario, installed without Midwest Expansion, and I can still do deliveries to Canada via Detroit, and other cities because the game just plots a slightly longer route around the Great Lakes region where the roads do exist.
You can also make manual routes as well. If there is a particular delivery you are interested in that is near an area with broken roads, you can teleport there (officially or using the dev console), pick up the load, and then manually plot your away around broken roads. The game will always plot a route that avoids broken roads, so you can use that as guide and fine tune it by hand in the nav map.