If it's mostly fully occupied you can get a full-doc commercial loan as long as it debt covers.

a property that was attached but the next door property had a door to the roof of it with a deck. 

If no, are there photos of each unit and all closets, the basement, the roof, the exterior, and all mechanicals?

If they have a good roof, I use a company that used to send someone out to do a roof inspection (at no cost to me). 

You tried getting a roofing job from Bob Prisco aka Bob Stevens, or you tried getting a roofing job from Elliott Taylor?

Build an emergency fund to cover unexpected costs, and ensure you can manage the mortgage without STR income if needed.

I’d have a better picture by sitting down with someone at a bank, but I did a calculation online and the new loan on cashing out $130k would still be covered by the current rental payment.

Flooring, Drywall, refinish basement, roof, gutters, tuck point around house, and one full bathroom gut all had to be completed. 

Otherwise, you won't have the extra funds necessary to cover the rising costs of goods and services in the future.What causes rents (and prices) to increase?

There are definitely some pockets of fairly priced duplexes to at least cover some of the mortgage, but tough to actually come out in the green monthly if you’re living in the other unit.