Retirement accounts are designed to be invested passively so when the IRS sees you running an active business in it, to level the playing field between retirement accounts and other business the retirement account incurs UBIT. 

Seems like you are looking for a passive income play. 

I just feel like everything that I am looking at has to be a high effort strategy or an equity/value add play.

Appreciation in most Sec8 neighborhoods is very low so it’s a cash flow play.- I would highly suggest you plan on using a property management company.

Step up in basis to reduce your heirs' taxes and morePlus the real estate tax "deferral" can end up being permanent if played correctly

You're not in the position to be a cash buyer...as a former wealth manager, it's simply not a good play for you for many of the reasons stated above and more.  

To avoid scammers and fraudulent paystubs, I contact the applicants place of employment directly to verify that the paystubs are accurate, the company is legitimate, and the duration of the applicants employment.Why do you need TWO YTD paystubs?

Do number, size, or area of investments owned play the biggest role in that decision? 

Rate and price play a big role in BRRRR.

REI is pay to play.