But I'm also producing good cash flow, which I plan to first save and build a good 6-8 month emergency mortgage fund for both my rental property and my primary residence.

This tenant seemed really nice, let me in to inspect the unit, but already started talking about how they were trying to find funding to help pay the rent for July. 

Self fund your reserves with savings and the cash flowsI get that but also a line of credit is like an emergency fund. 

@Stephanie Crawford at Movement Mortgage, we have a quick and simple low doc 5-10 business day close HELOC that you can use for this to avodi the headaches of the big banks!

They give great examples but are low on the how-to.

It is a double close transaction where the 1st position lender will not fund until the 2nd position seller docs are signed and funded.  

Do we, instead, put as low a down payment as possible (owner occupied financing) and buy several cash flowing REIs to cover as much of the new higher mortgage as possible, using the chunk of equity from the sale of the SFR?

There is high risk, moderate risk, low risk.

In many locations, including some of the other hot-housing market cities, appreciation has made homes unaffordable to those who don’t own a house they can sell for the funds needed to make a move.

There are no low hanging fruit deals these days, you have to make things happen.