I was wondering if anyone has started a storage unit business and how it went for them.

The rules are different.If she owns the trailer, she might be legally able to hire a company to move it to a storage lot. 

@Cheryl S.Rental properties are set up as classes.If you want, you can set up tenants as customers.Accounting Software Recommendations - Quickbooks(Desktop), Quickbooks(Online), Stessa, XeroOnline Storage to save receipts recommendations- Google Drive, Dropbox, Apple DriveExcel - to save information such as tenant name, lease start date, current rent, etc

In my case, I have residential rentals in one LLC, commercial properties in another, self storage in a third, and my real estate company operates in a fourth.

We've been doing about $1 Billion in volume annually, about half to 2/3 multifamily and the rest storage and MOB.

In the same note...how about extra storage units in the back of a multi unit?

I also considered commercial real estate such as storage units.

However, when the iron filter flushed through the water at midnight, one side had water all over their basement storage room and soaked into the carpet.  

Added recessed lighting, ceiling fans, additional storage, landscaping What was the outcome?

In my case, I have residential rentals in one LLC, commercial properties in another, self storage in a third, and my real estate company operates in a fourth.