Definitely look into HELOC/cash out options, but if those don't work in terms of rates or availability I'd suggest using the existing cashflow from your multi to offset a primary mortgage, and then find a primary with an ADU.

There are several benefits of having cash in the bank/liquid reserves versus an open end mortgage (a.k.a) credit card.

near 0% and 0% options with DPA's exist (down payment assistance) programs.

i wasn't buying this as a start to my real estate career just to help me with the mortgage.

This might be a rookie mindset is it bad I don't care for cash-flow at the moment in my eyes if someone helping me pay down my mortgage and build equity I'm okay with that.

The other attempt at affordable is density through what they call their middle housing zoning and up zoning existing parcels. again led to building boom but still nothing sells for much less than 500k.

Suppose you have $46,000 mortgage at 8% interest on restaurant, $22,900 SBA loan, $3,900 at 1.75% interest on a microloan, $23,00 on temporary 0% interest credit cards all for the same business totaling $95,000 in debt. 

There is a recorded mortgage and also a promissory note.  

Are there any features you’ve always wished existed in tools you currently use to evaluate investment properties?

@Josh WillisHouse hacking involves buying a small multi-family property and renting out units to cover mortgages.