If you have not owned it for 12 months it can be supplemented with a Airdna report or the appraiser giving a short term rental estimate on the 1007 report using short term comps in the area. 

In many parts of the country AC is not needed in a basement and you could use supplemental heat sources

Just need something to supplement my retirement

All the generic information they provide is useless with out someone to walk you through it and show you how do implement it. 

I helped 37 clients buy or sell multi-family last year and in my experience from these and many other is that those people who want to build wealth and supplemental income through rental properties usually struggle the most with saving the next down payment, which is the true value of these live in loan options at 3.5% (FHA) and 5% (conventional)..  

Unless a generic lease form is made available by the relevant state real estate commission I would engage the services of a real estate attorney to draft a lease template with wording specific to mid term rentals rather than trying to modify a lease meant for standard 12-36 month rentals.  

They are going to be supplements to other steams of income in my retirement.  

I own a primary residence on Maui and am interested in building an ADU to supplement income after losing my vacation rental condo in Lahaina.

And I mean in a generic sense, not a going green sense.

Do you know if they are using all of your income including overtime, bonuses, higher income if most recent year is higher. 1099 income can be tough for some lenders since they use a generic worksheet and do not do the math correctly.