The principal has hired an attorney years ago not sure what she has done.

I also plan on applying my net rental income towards principal only payments to shorten the life of the loan.

I have looked at Hopatcong however despite allowing STRs, it has language that requires the STR to be the principal residence of the owner as indicated by something such as a diver's license.

Yeah, I get the infinite banking principal and see many others leveraging the concept. 

It's crucial to evaluate how the deal performs with the new mortgage:Updated Financials After Refinancing: Market Value: $459,000 Mortgage Amount (80% LTV): $367,200 Equity: $91,800 Interest Rate: 5% (30-Year Amortization) Assuming after 12months the rate will drop to 5%Monthly Expenses: Mortgage Payment (5% Interest): $1,971 (Now you are paying interest and principals) Property Tax: $260 (assuming has been increased with a 4% from last year) Utilities: $361 Insurance: $104 (+4% Adjustment) Vacancy: $166 (now after 12 months we can assume we have some vacancy at 5% factor on annual rent) Repairs & Maintenance: $166 (now after 12 months we can assume we have repairs at 5% factor on annual rent) Total Monthly Expenses: $3,028Rent Income after 12 months assuming annual rent increase at 5% : $3,323Cash Flow: $295$ per month 😊Long-Term Gains: $5,418 Principal Paydown year 2 (this will increase each as you pay off your mortgage $36,720 Property Appreciation (assuming 8% per year) $3,540 Cash Flow (this will increase as rents rise)Total Annual Return on Investment: $45,678 with just $ $22,789 remaining in the deal.

Interest always paid on time, and principal was returned with bonus right on schedule.

The note investor who thought interest is paid on the original principal rather than the unpaid principal balance.  

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).

Penny Penny, PLEASE take a moment to go to the Syndication FORUM here on Bigger Pockets and read the innumerable stories of investors who have had their distributions stop shortly after investing, lost principal, or now have their capital tied up for TWICE as long coupled with no distributions. 

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).