As you're looking at properties it's best to identify multiple potential replacement properties to give you more opportunities and alternatives. 

Like you said, probably not so easy here in MA but you did give me an idea about alternative uses...I typically focus on properties that I can make buildable by solving zoning issues, access issues or minor wetland issues.  

Your goal is to build a passive real estate portfolio (we can discuss what passive means to you), so while I don't condone throwing $100k into a deal without even a basic understanding, alternatively doing so will teach you far more lessons than reading a book will.  

Alternatively, I have spent the last decade doing technical work in cybersecurity, and can land a job between $140k-$190k (depending on where in the US). 

Each has their own tax implications.There are some alternative methods of calculating how much of the distribution and therefore the interest expense falls under this category, but the bottom line is that it is very important to keep track of. 

Perhaps do a case study with a hypothetical deal you think is typical for what you are looking at and compare it to the alternative investments you might use and their expected returns.

An alternate viewpoint is that the group is closing so many deals because they have an edge in a competitive market.

Over time, I’ve accumulated more cash reserves and don’t need as much flexibility, but I’m actually in the middle of a refinance right now using an interest-only mortgage—because the pricing with the lender and the corresponding ARM is more favorable than a comparable principal-and-interest loan.The key with these alternative or "exotic" mortgage types is that you need to be financially savvy and have a solid plan.

Or of any alternative strategies to make this work?

So, you're actually making the argument *against* debt (not for it).I think you mis-understand debt, risk and the alternatives.