I supplement those with STR bookings to fill in the gaps.

First, let me say that real estate sales is a great profession with unlimited earning potential and you have the ability to create your own "pension" with contractual recurring income with rents with your own properties or supplement your income with rehab projects on your own fix-and-flip properties. 

Just treat it as a supplement, not the main event.

I'm looking to supplement my income with one property at a time, however Redfin and Zillow only give a few houses that could even remotely bring a profit on a renovation.

Also Zelle doesn't allow for the ability to individually enable/disable a tenant in the system.Money orders require driving over to pick up, or the tenant sending them late and then the late fee issue is still there. 

A slightly smaller living room that enables an extra bedroom or better bath access will usually outperform in both occupancy and nightly rate over time.The compounding effect is real too.

The city where you invest and the property you select will determine whether you can achieve a rental income that enables long-term financial independence.

At what point does “working with tenant” become enabling a default pattern?

One option is the outbound marketing approach, which can include pulling data, cold calling, texting, door knocking, and several other strategies.I’m happy to speak more about what has worked best for us and what enabled us to build a full-time business in wholesale real estate!

We've enabled security deposits via Ownerrez on Airbnb and VRBO listings for about 4 years now.