You are discriminating against the amount of income not the source. 

@Alex BellYou guys make a killer income, congrats!!

And he gets the income off the deferred tax while he's alive.2.

On the other hand, a cash-out refinance of your current duplex is another avenue to explore, albeit with considerations such as the risk of losing your low 3.5% interest rate and increasing your loan amount and monthly payment, thereby reducing your current positive cash flow.

But now I'm wondering if all of those are reduced to 5% down. 

I would add in the ability to add an ADU later in the property to boost the income 

By looking at the numbers you gave me above, you can cashflow and your rental income is 1.1% to 1.3% of the purchase price.

With every unit you add the next comes faster because of increased income and financing opportunities (equity). 

I would be interested to see what your credit and income would be because we have heloc options and I may be able to help.

Can you afford to give up that income that you are netting from the STR?