As an out of state investor, I would love to connect and potentially have a property manager in my team that experience in Section 8 rental. 

Property management is a "nickle" and "dime" business.  

We have an STR/MTR management company in Indianapolis.

It should be included in the monthly management fee. 

This client chose not to use our services and instead, tried to self-manage their primary.

I personally believe that a better way to jump into mid term rentals is to take a course on buidling a property management company or cohosting business where you bring your skillset to the table without the intial investment into all the furniture and leases.

Is anyone aware of any of a property management tool that allows PMs to give discounts to tenants who enroll in autopay (similar to how major US phone providers like do these days)?

This is more of a local technique.

The guru your son is learning this technique from is likely not telling your son that the deal will almost certainly encourage your son to get an "off-market" deal from a "wholesaler" who is unlikely to properly disclose the details of the property or encourage an inspection. 

We are extremely unhappy with our property management company.