But by then my wife became a stay-at-home mom and my DTI prevented me from getting larger mortgages. 

Give it a year more or so and that rental income will go up and with lower rates, the numbers will make sense for him if he refi's.And for the larger properties

You can run multiple small deals at once, or run 1-2 larger deals at the same time.

This probably sounds a little like wholesaling or being a Realtor, and it is.If you don't want to spend $1,000's to build this out and take on the associated tasks, there are other, more cost effective, options.I'd recommend looking for potential deals via free (or low-cost sources) i.e. local meetups/networking, Courts (probate & lis pendens lists), Realtors, Wholesalers, properties for sale online (especially those with 90+ days on market), etc.All the best!

As the deal size gets larger, this should get lower. 

1) It's not unreasonable to end a tightening cycle with a larger rather than smaller drop.

I'd like to use these to upgrade into something much larger in the next 2-4 years. 20+ units.

What would be interesting to me if a software/program could do this analysis at a larger scale in order to identify off-market properties that have "below market" rents that would help prioritize someone's off-market focus.

We specialize in working with REO, real estate agents & brokers, institutional & private investors, and homeowners, offering solutions that meet the unique needs of each project.At Nuovo, our core values are at the heart of everything we do:Vulnerability: We maintain open lines of communication, ensuring transparency throughout every project.Integrity: We approach every task with honesty and a commitment to doing the right thing.Innovation: We constantly seek new ways to improve processes and outcomes.Adaptability: We embrace change and are always ready to adjust to meet client needs.We believe in creating a fun, open, and trusting environment, both within our team and in our client relationships.

Lastly, my initial goal is to house hack so I can theoretically live free for a few years, while buying multiple MFH to build a larger portfolio quickly.