If the parks are older, be sure to check the infrastructure (i.e. plumbing pipes, electrical, gas, etc).

Nearly all lands within a couple miles have now been built out, and it's all residential and lower impact commercial such as banks and churches, no gas stations or Walmarts.

I'm still working on getting some numbers from the owner but as of right now, what I have is that all units are rented out, tenants pay for power and the owner pays for water/gas/sewage/trash.  

Find NNN that are Amazon-proof with strong sales (gas stations, QSRs, etc) and you'll be ok.  

So I’d get dropped off on a Saturday morning to change the locks, with a mower (extra gas), a ton of trash bags, and a bucket of paint.

What I typically write up when investigating a property is the following:VACANCY: 7-10% (depending on where the property is)MAINTENANCE: 10%PM: 7-10%Some other expenses you should look for are:Taxes, insurance, water/sewer, garbage, electric, gas, advertising for units, lawn service/ snow removal, accounting or legal fees. 

@Charanjit Singh if this is an off market deal that you have control of and the seller is motivated and the area is urban, negotiate with the owner to drop the price so you can cover the cost of converting to gas with 3 meters.

Roof still have 10-15 years left, new gas furnace, new ac unit central air.

Find someone you trust and is smart enough to know what to do in your place.A sibling or best friend should do fine.They should know how to shut off the water,gas and electricity by locating the manual shut off valves and switches.They should have a list of phone numbers for handymen or other repair persons that you have preselected to come in an emergency.They should have keys to every door and lock as well in case repair persons need access to certain areas.Minor repairs can wait until you arrive home.

Because u have to think about their finances: Rent, gas, electricity, cable, car payments, children and now water/sewer?