3) If I can find a private money lender to do a 2nd mortgage, they will need a high interest rate.

Neither property will be cash flow by the time we are moving out (unless rates drop dramatically and we can re-finance). 

Guarenteed payments on the 1st, keeping up with market rates and mutual interest between the tenant and landlord to keep the property in good condition and to keep the tenant living there. 

I am looking for a fillable rate sheets to enter owners rates for them to approve?

They indeed got a response-rate of close to 50%.

Qeustion: Without a 35-40% down payment, would it be advantageous to buy down the rate? 

Without question the Pandemic fueled activity and mortgage rates drove investment and inventory of STR's and vacation rentals for rent up in many destination markets. 

If considering appreciation and buy and hold for 10+ years, and looking across my entire portfolio, I can afford to have negative cash flow on one property, while providing a good quality property at affordable, below market rates.

The AIO is our only debt on the property and is in our personal name (not an LLC) as a requirement of the loan.We are looking to do an extensive addition/remodel on our personal home, and given current rates, we are considering using the AIO loan to help pay for it. 

There are so many more questions to ask such as your personal income, savings rate, etc., but let's take this on the surface.