@Douglas KrofcheckIf you have four separate units and wanted to install a central vacuum in each, it is possible each would need to be plumbed separately {for fire code reasons} - either back to a common mechanical room or within each unit - requiring a separate canister/motor to be installed for each.While a central vacuum would be a nice perk, I doubt it would be cost effective - it would likely be cheaper to finish all the units with hard flooring (no carpets) and buy a $50 Bissell Power Force bagless vacuum for each unit.  

I would investigate making this into a partial motor home camp ground along with installing a few sites with trailers visitors and over flow from the camping community which will yield a cash flow if advertised in Good Sam's directory as well as others.

I rent a storage building for my staging furniture and they have a large lot full of motor homes, boats, trailers, cars, trucks, etc.Another idea if you like farming and the land will support it would be to put some kind of livestock on it (cows, goats, etc).  

Oh My we must have encountered the same reimeetup daily email people selling properties. " YOU will need a drill motor to get in".

Or motor oil on the living room floor. 

This is not my first rodeo in the Motor City- I own a house there that I purchased in an auction for $500 in 2014 and did a live-in rehab with my fiancé (now wife) for 2 years before we moved here.

Junk yards typically have battery acid leaks, motor oil leaks, gasoline spills and other items relating to electronics.

It's somewhat different than my area in that there are more people, businesses, the Speedway, etc. in your area (though we do have Shelor Motor Mile Speedway here).

The building next to it on the right (further up north) is used by Jaguar and British Motors.

For newer ECM motors, blocking vents can increase static pressure in the system which means the unit's blower must work harder to continually provide conditioned air to the home, thereby reducing the efficiency (and more likely, longevity) of the unit.