Contact the zoning department and see if you can get the property rezoned as a duplex.

Would you eventually scale down to fewer properties with higher cash flow, or continue holding indefinitely?

Vacant properties are targets.

We currently have 3 properties.

It's more important than doing individual property analysis, because when you do a proper market analysis, you are analyzing ALL of the properties in any market(s) at the same time.Now, one of the analysis "pitfalls" is not understanding what defines a market, or more importantly, a Micro-market.Another problem is focusing on one strategy, and trying to fit each market/property. 

Financing your second property can be tricky since lenders may only count 75% of rental income toward your debt-to-income ratio, so get pre-approved early.

After much consideration, I've resolved to take action and pursue a BRRRR property.

Verify that the info of that landlord is correct through property records. 

I have purchased 3 properties in Costa Rica.

I would much rather add a property to my portfolio..