Some smaller local banks have tight upper loan limits and thus stick solely to single family. 

You would still be able to qualify for non-qm loans like DSCR products which are based solely on the appraised cashflow of the subject property, (and having > 600 credit score).

May I ask you if there is a source to find the *maybe* more expensive but reliable contractors who are prepared to be repaid as the job is done?

I support the change.As a host and regular guest it is a constant source of frustration when me or my guests can't compare apples to apples on what a place costs. 

The source of a deal does not make it a deal.  

Also, the background you are presenting sounds like it should not be an issue to obtain a residential loan.I would suggest building that credit up, not opening up any other lines of credit and create a portfolio that you can show to the lender that describes all your sources of income.

If you put 3-5% down, you will need to live in the property-you can't use it solely as a rental. 

Yes, you can use sources like rentometer and Zillow rental manager to try to comp similar rentals and see what the market appetite is for a comparable unit.

@Marta Cieslak are you looking to source investment property?

I'd also recommend researching "asset-based" lenders which evaluate a decision to provide financing based solely on the house and deal itself (not your personal income or financials).