Unfortunately, my options for small multifamily properties here are limited.I’m now considering buying a single-family home on a lot over 8,000 sq ft and building a duplex in the back to generate rental income.

And why 20-80, is that some magical ratio, or perhaps it's backed up by some sort of statistical analysis? 

You want someone watching your back here.

@Kayla M. sadly as other have said, often out of state investors are paying more than is worth, and it can be tough to get back out of a deal.

The investors can get back to whole, it’ll just take time.  

However I think you have laid out a more in-depth understanding of these traits than CM even has.     

I can always go back to our attorney and ask for clarification on the language, but following your thinking, this is what I'm coming up with.Days 6 - 10 would be $1550 * 18% = $279 / 365 = $0.76 per day. 

I have to take a step back and realize how blessed I am.

When I made some changes to the property and put it back on the market about 15 months later for double what I paid, it was under contract in 48 hours.

When valuing the property, focus on its net operating income (NOI) and use a cap rate that reflects Section 8’s stable, government-backed rents.