I don't think rentals are a volatile investment. I know people who own many rental properties in a couple towns just outside a military base. They only advertise the rentals on the base, so they can get military people for renters. They never get beat on the rent and the military people always take care of the places well.

Even w/o the government looking over their shoulder, most people I know who have had rentals haven't had problems, as long as they don't rent to friends or family and they do credit & background checks.