This could be also measured in total profits including ROE vs cash flow alone.

What other measures would/do you use to calculate ROI on this type of property?

I've been reading "The changing world order" by Ray Dalio, and listening to some podcasts related to the subject of the declining US empire, and I'll admit it has me wondering if everything we hold true about long-term investing may be in for a shakeup in the near futureWhat I'm trying to decide is, should I sell a rental duplex (I have 2) and pay off my primary as a defensive measure?

But you need to be even keeled and scrutinies of where you put your money, so measure a hundred times and cut once.

Additionally, government stimulus measures have led to inflation, driving up the prices of everything, including real estate.Why aren't prices coming down?

I think your goals are very realistic and measurable.

Is there some type of measurements as a guideline to specify what is consider within the “Geograpgic Area”?

The 2 garage  measures 17'x20'.

Slow, steady, measured growth to that level is doable and I wish you all the best. 

There are lots of ways you get returns as a real estate investor, but to replace your active income you’re generally going to focus on your cash on cash return - or the amount of money you receive every year from cash distributions.In this example we’ll use $100,000 as your annual income that you’re looking to replace.Cash on cash return is measured as a percentage of return from cash distributions per year based on the amount you invested.So let's say you invested $50,000 into a deal that has a 5% cash on cash return, that means you’d receive 5% of 50,000 that year, or $2,500.