We also have strong financial services (banking and insurance) employers - Key Bank and Progressive Insurance are based here to name just 2.  

Adam, usually if you have a 401k at your current employer they restrict your access to the funds.

Though you say cash transactions, you'd never be able to place the money into an account.That being said, the IRS compares data to other agencies, just like employers are required to send W-2 information.

Especially a stable employer like Amazon. 

For every 2 dollars you earn (profit on your rental or employment income), the bank will lend you 1 dollar of payment (in the form of a loan).  

It sounds like the Lone Star project is on the rocks as of yesterday, but the area is still being gentrified and increasing in value, so it might still be a good place to employ your model.

How much should one expect to pay for health insurance if they are a full time self employed real estate investor?

@Joshua HilliardIn order to participate in a solo 401k plan, part-time self-employment activity is required.

While I agree with @Ryan Groene that an hour drive to the major metro puts you outside the idea commute radius, are there any major employers closer or more affluent suburbs of the metro area that need to employee firefighters, nurses, police, tradespeople ect..?

I have heard both sides - half of the people saying RE will trend upwards for several years given gainfull employment opportunities and a adventageous business climate along with a continued shortage of housing; I have also heard to wait to invest until around the 3rd quarter of 2019 when housing is more abundant and the economic trend demands a downward curve.