Understanding their cash flow is critical.I especially like your idea of communication clauses—non-responsiveness is a huge red flag, and setting expectations upfront can save a lot of headaches later.

Rent out part of the space at least to help pay for mortgage and utilities.  

There is a contract that is signed.These are "quick" transactions, within days, that the borrower (Subto student) needs "immediately" to provide a non refundable emd, for a Subto transaction.

I read some old posts where folks have suggested using non locking door knobs is that something tenants like ?

It explains why very few flippers are adding single ADUs and if they are they are usually a conversion of exhisting habitual space (bunk houses, detached offices, workshops, craft rooms, etc.  

These loans are not allowed in non-owner occupied scenarios. 

I can imagine that, with the wrong mindset, it could feel like an invasion or disrespect of your personal space. 

While rates were near all time lows, we bought a home that we could reside in and rent out the backyard detached living garage space.

Lending favors w2 employment.Self employed have; Non of the above. exactly my point if your going to be self employeed you need to make a bunch more than your salary with bene's.

There are plenty of cash-flowing markets here - especially in the STR space.