Throw in the fact that properties over the next few years most likely will have very low to zero appreciation and they probably do not get you a net of $6k a month even if you considered the principal payments you are paying down and lending right now is a far better situation to be in than owning property - just as the opposite was several years ago during very low rates and high home appreciation. 

The first monthly interest installment of xxxxx due on or before April 15, 2024 and continuing in like consecutive monthly interest installments of this amount for a total of one (1) year or twelve (12) payments at which time the entire unpaid balance, including Principal, accrued but unpaid interest, will become due and payable.

NOTE:  there may be some tax on interest or principal on the payments--seek professional advice.Also, stress there will be no inspections or other contingencies--sell the 'peace of mind' side of the equation.You have known each other for 12 years and you established you are a great payer. 

This will lower interest costs and free up future cash flow for reinvestment or reserves.Tax Planning: Work with a CPA to mitigate tax impacts from principal-heavy payments and potential gains.

I think paying off a loan with a high interest rate debt and adding to the principal is one way to stay liquid within the property. 

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).

At full occupancy, the cash flow I just keep in reserves for repairs or help pay the principal. 

Here’s my question: Should I use my w-2 income to pay down a lot of principal and re-try to obtain that HELOC?

If the economy gets better, you might be able to refinance and/or if you make more money, pay down the principal later if that is what you really want.

There are certainly investments you can make to increase the principal in the net 5-7 years.