I don’t think density matters as much as you think it does. The evidence seems to be that people are mostly contracting the virus in indoor spaces like offices, restaurants, theaters and churches, and people in low density areas go to offices, restaurants, theaters and churches that are just as crowded as the ones in cities. In high density areas people live in smaller apartments that are stacked on top of one another, but it’s not like the virus is percolating through the walls and ceilings of your dwellings. The only real difference in exposure to the virus is public transit.