Calculating ROI (CoC, Flow, Appreciation, etc)Would love to know how, and how often people are looking at the numbers to determine when to refinance, sell, or just track performance. 

Interest is always taxable, no matter how small.

The 3xs monthly rent rule is an outdated calculation from a time period where income to living expenses evened out.

This is because your rental income is NOT calculated as simply as taking the rent minus the payment OR by simply taking the negative number on your tax returns. 

I have identified an ideal location, and the agent has informed me that the rent is $45 per square foot NNN, plus an additional $5 per square foot.Upon calculating the total annual cost, it appears that I would be responsible for over $80,000 per year.

Which BP Calculator did you for your analysis?

I am not sure how the owner occupancy requirement of the JADU impacts value, but is will impact value as there are many RE investors who do not want to owner occupy.You should be able to determine the value by calculating NOI and knowing the market cap rate.  

As long as you have a primary housing expense (either renting or own) you will be able to use 75% of the appraisers opinion of the future rent. and you will be able to add back a decent portion of your paper losses on your tax returns for the properties you already own using this form:  https://content.enactmi.com/documents/calculators/Form1038.C... 

If short term rentals are truly where you see your future, making a calculated shift might be the right move, but ensure you're not jeopardizing your financial stability in the process.Hope this helps!

Here's a bit more in detail about how rates are calculated for DSCR loans:1.