Someone trying to earn 4-5% return they could get from a bank cd?

There are a few banks in HK that are also located here in the states.

It markets our properties, screens our tenants, collects our rent, deposits it into our bank accounts, has full accounting and reporting features, has a tenant facing web portal & app where tenants can log in and report maintenance issues and see their account, etc, for $2/door/month - but they have a $45 minimum monthly fee... so up until you cross 22 doors it would be $45.

I've done it multiple times on primary residence and was just able to do it on an investment with a local CT bank. 

This is already going on in banking.

I don't want to see you bank on having multiple un-related renters and have your plan fall through in the first few days. 

I would talk to the bank first.

Many banks limit personal loan amounts.

A local bank relationship How did you add value to the deal?

You can probably just go ahead and live in that 5th unit, but I believe whenever you go to refinance it with a bank or what not, the 5th unit will make it require a commercial loan and not residential regardless of what the county records show the property to be.