Would like to house the additional units in the basement, electric baseboard wouldn't really work for a decent sized 2 bedroom unit.

Your strategy is good, and you are looking at a town that's affordable... but remember there's always a reason properties are very affordable when only 20 minutes away, properties are selling for double or more.  

Usually double what you expect it to be is what ends up happening. 

If there is a pressing situation that requires you to sell to get the cash in your lifetime then it is doubtful that you will squawk at having to pay tax at that time.But if your tax is in the $120K range and you get to invest that for a net return including of depreciation benefit for say 8% then after 10 years you will have more than doubled that tax in return and compounded interest. 

My goal is to at least double my units by the end of this year, and achieve full financial freedom for my family by 2026... though I'm hopeful that as I keep learning and growing, it will snowball even faster than that.

I have an opportunity to purchase a single family home, 4 bedrooms/2 bath home within 3 minutes of UAH campus in Huntsville, AL. 

Around here to move a singlewide is around 3k, and double, 4k, to move them 25 miles or less.

@Trevor Baker I would definitely double check your build costs.

That just increased 40% of $5M in my estimation,  with the doubling of the estate tax exemption this year, to $5.3M in taxes he would have SAVED.    

Click Here to view the full storyBy Jason Bolton – Data Editor, Memphis Business JournalAug 9, 2018, 12:04pm CDT Updated Aug 9, 2018, 1:51pmThe number of people who rented versus owned their housing increased by about 5 percent nationwide from 2006 to 2016.In Memphis, the number of renters increased by more than double that amount — 11 percent — over that same time period, according to an analysis of U.S.