If you do find "licensed, bonded and insured" contractors that are willing to work for nothing! 

Your mom's gift to you has given you the opportunity to skip some of the early boot strapping, teeth rattling, sleep losing all in, risk it all growth efforts.  

IF you are willing and able to invest the years of time, effort, and money and IF you are able to perfect your systems and get a good team in place, then at that point it can be profitable and passive, but understand that those are a LOT of IFs ... you need to go in with eyes wide open to this fact, and not expecting it to be like buying a stock or a bond ... and no, buying turnkey does not excuse you from the necessity to do this, because the turnkey company's systems are optimized to maximize THEIR profit, and not necessarily YOURS.

Do your parents invest in the stock market, bonds, or anything?

Not to mention your possible requirement to be bonded and insured.

The good thing is that all the "custodians" (as they are referred to) have great education sections on their site.In a nutshell, the 'true' self directed IRA/401k allows people to use retirement funds to get involved with more forms of investment rather than solely stocks and bonds.

If you are familiar with bonds, it's not a giant step to buying notes.

It’s like pulling teeth with him.

In finance, you can calculate the cost of equity using CAPM and cost of debt by looking at bond yields because there is such a highly analyzed public market.What can we assume about real estate investment discount rates?

HML, syndications, crowdfunding, and a robo advisor for exposure to equities and bonds like Betterment or WealthFront.