I own a very large RV Storage Site in Smaller Industrial Park, just North of Fredericton, NB, Canada.

@Kendall ButlerYou don't have to invest in your local market, also there are different ways to invest (rentals, private lending, multi-family syndications, self-storage and mobile home parks, etc).

I would send her a letter advising that the hallway is a common area and not available for the storage or placement of her personal belongings at any time. 

@Shane CrockettFor improving NOI, focus on reducing operating costs or increasing revenue without added operating costs.As an example, you could reduce electric usage by changing all common area lighting from incandescent to LED.To increase revenue, we added some onsite storage units to rent to the tenants.

If you are finding costs to build are high, make a smaller but super well designed unit (think storage!).

I have a 5 unit apartment building complete with a separate laundry room, utility room and individualize large storage rooms on site for each tenant. 

I drilled the well, installed a 5,000 gallon water storage tank, purchased a metal barn for $39,000 and graded a pad and driveway for the house.

I do not trust internet storage to be hack roof.

I always wrote off town homes as being not feasible investments as the HOAs would cause issues and cost too much.

It's shared storage space with another tenant, as designated by the landlord, but not common space available to the landlord and/or manager.