I am in the preventive maintenance camp mostly because it lets you plan the impact to cash flow and take advantage of lulls in the schedules of service people or sales on equipment. 

For 20 years we just held there my father's construction tools and equipment.

Give each unit a shed so they have someplace to store lawn equipment.

Not to burst your bubble but by the time I was 12 my brother and I had already purchased a nice farmhouse with several outbuildings capable of raising livestock, acquired the equipment needed to run the farm, and paid cash for everything.

---------------------------------------------------------Land ($18/sq ft): $941,000Construction ($180/sq ft): $1,260,000Engineering/Architect fees: $70,000Legal/CPA/Permits/etc: $40,000Cost of acquiring finishing equipment (security/signage): $30,000Marketing/Insurance/and other misc: $30,000---------------------------------------------------------------Total Project cost: $2,371,000

There will be a return at some point of the accumulated demand of people who were unable during the confinement to go out and buy furniture for their home, paint or repair their house or, on the industrial side, build structures and install the necessary equipment for the business.

I hired a professional company, but I don't know the exact technique they used or the specifics of their equipment. 

It will makes its way behind closed doors and into every space of the home no matter what you do w/o specialized equipment.

Check if there was a permit obtained for the install of the AC equipment.

Only thing I'd ever rent to a friend is insured equipment or something I don't mind losing haha.