Can I still run a background check on them at all? 

I'm sure you are already beating yourself up about not doing the background work.

While I understand that I come from a fairly long and hardened institutional background, I am absolutely astonished by their apparent commercial success.  

I did do a background check, credit score, and talked to the previous landlord to ensure they are responsible.

For screening, I use either Zillow's application process or if not coming through Zillow, apartments.com to run the credit and background checks.

That nice looking patio in the background of one of the photos ... can they sit out there?

Im assuming Credit score, full background check and eviction. 

You want someone with a nice headset so that when they are on the phone there is no background noise.5.

Background: My wife and I have managed 3 properties in N GA since 2021.Has anyone ever included customizable add-ons within their STR listing as a way to differentiate their listing but also increase profit?

For someone with your background that has built companies, I can imagine completely handing off control in a syndication may be challenging.