Will this be enough or is there another program that is better aligned with the real test material?

We can easily cover the mortgage with our W2 income and we anticipate we will cover the mortgage and then some with the STR income (it has a track record of this with current owners and also comparing data from surrounding comps).

Check out AirDna and pricelabs to see what the rental data says$300 is crazy high. 

I am just wondering where Bigger Pockets pulls it's market data from?

One basic question I have is this: How do I test my assumptions, particularly in terms of rent amounts? 

Yes interest rates are low and so is the monthly loan payment, but the costs to keep up the house and taxes are going up, so this data point is appears lower than it should be.

Both my full time job and side gig require story telling with large data sets, I have a vast understanding of excel so would be more than happy to help with data analysis and can show you a neat shortcut or two!

Walk the properties with your agent and they will likely be able to give you a "sniff" test of what the property requires.

I can look at the data until I am blue in the face, nothing beats first-hand experience. 

I would reach out to a local mortgage lender so they can give you cold, hard data on your refi.