If this is your first investment, LTRs are much more predictable and passive, might be a better place to start. 

I have a spreadsheet set up already but the "Short term rental, long term wealth" book didn't go into that much detail in estimating gross annual income.

Then have a high savings rate by limiting spending to what you prioritize and maximizing income by focusing on what you know. 

Choose the right property: Look for a property that can generate enough rental income to your mortgage and expenses, ideally with additional flow.3.

Specifically discuss with your CPA the ability to deduct depreciation expense over time, allowing you to deduct a portion of the property's purchase price as a non-cash expense, meaning you can lower your taxable income and potentially lower your tax liability.In other words, you can reduce your taxes by writing off expenses from your total taxable income.

One strategy to consider to boost the rental income is to rent out by the room. 

However, I spend a lot of time managing it as I am renting out by the room and the tenant profile is lower income.

There is no employment, income, or any debt income show on these applications.

Looking for some others experiences with rent income appraisal for qualifying a DSCR loan....

Yet, interest payment on mortgage offsets the rental income (I don't want to pay income tax on rent), and there is a chance of refi later.