, insulation, ADA, storm ponds, fencing, insurance, financing, NNN, market, road access, etc.  

The idea of running a little water to keep things from freezing in the cold is common.It seems that practice was a contributing factor in this mess: https://amp.bangordailynews.com/2018/01/31/news/midcoast/maine-mobile-home-park-residents-weigh-lawsuit-over-water-problems/I'd look into a thermostatically controlled heat tape system on all the under trailer supply lines, along with insulating the lines.

And why is this sector somewhat insulated to the impact the recession had on other market sectors?

Okay.... suck out the litter box in the attic, replace all the ceiling drywall, re-texture, repaint, and blow in new insulation. 

Each LLC carries a blanket liability policy so I’m well insulated.  

And I had insulation on them. 

New plumbing, electrical, roof, insulation, the works all done correctly with quality materials.

The roof have no insulation.

Our knowledge is that the previous owner insulated half of the building and then quit (probably ran out of money/effort).

Now people actually look at roofs and insulation more than kitchens and bathrooms!)