It's the same fuzzy math my wife uses to justify a new pair of shoes. 

I’m considering sectioning it off for storage units for the tenants or possibly even for the general public if there’s not enough tenents wanting storage. 

I’m saying you are going to fall, learn to tie your shoes tighter or get a new pair.

Needs a property with the following characteristics: a lot that needs to be fenced for security, office space for 2 to 3 people and storage space for business supplies, at least the size of a two-car garage.

Additionally, it's funny that you listed Storage Units since I've been fascinated by them as an investment since high school.

All the charts showing what happened when paying off the property vs. not paying off the property assumes that the earned rent just gets put in a shoe box and sits there. 

I looked at mobile home park I got outbid on by 400k on 80 acres and our plan was pair more lots with storage and also nonconforming billboards.

Mention the other benefits so they want to sign up (Free ACH transfer, Maintenance Tracker, Document Storage, etc.).I upload the leases and any other relevant documents like Move-In Condition form, state-required notices etc.Don't overthink it. 

Also, as mentioned previously having a locked storage closet at each property for convenience to restock units and then replace on a weekly basis makes inventory easier. 

I'm not sure how to use both spaces, but I'm sure I can charge for storage and garage at some point.