I don't think that would have been possible without have a long relationship with a single lender and a strong track record of performance.

In year two, it may still be too high if you claim any purchase- or setup-related deductions during your first year income tax return (i.e. say you net $20K on the Airbnb property, but you claim $8-9K in depreciation and $10-12K in furnishing expenses; the tax record will reflect that you lost money when you in fact improved your cash position by $20K). 

We closed out 2019 with a bang as median SFH prices increased by 9.93% over 12/2018 per MARealtor.com, showing up at $412,250, another record high.

I expect it is regarding the position of the loan in recording.

To get around this, you need to have a good relationship with a bank, and show a strong track record that you can not only increase the value of the property but maintain that strong performance.  

But you will need your name on title (deed from your parent's estate to you and your siblings recorded publicly with recorder's office) before you can get a loan.

And regarding "direct assumptions", there are no assumptions on the 15 minutes. 1)  I provided the form he needed to complete that I acquired from the actual investment firm I was trying to work with, it took *me* 5-10 minutes to complete it myself.  2) If he chose to just believe me and sign it only, then change my time estimate to 2 minutes to find a pen, sign it, and maybe photocopy for his records. 

When you sell a property your proceeds at closing generally will be 8-10% below the sale price due to 5-6% realtor commission, settling escrow accounts, county deed recording fees, etc.At 80% LTV you can get the mortgage insurance payment dropped, you open up the possibility of other non-FHA and non-owner occupied financing, you give yourself a cushion to sell if needed, and you reduce the possibility of being upside down if values pull back.  

I guess my question is it as simple as drafting a new promissory note and recording it or am I missing something.

She won't ever find anything because you would never do that (it's probably illegal) but she will stop her behavior believing she is being recorded and probably would move which is a shame, but you could probably recover from that.I'm just joking of course, or am I?