I would even say cold call some of these investors who owe many rentals and ask them questions.

The cost and time to move (even a few doors down) is not trivial.  

There are many other ways to qualify besides DSCR, like bank statement averages or even P&L statements that can offer lower down payments..check in with @Joseph Chiofalo he's a 20+ year mortgage colleague and can help with structuring and options.

If you're even considering this (which I do not), you should ask for an extremely high upfront payment (40% or more IMO). 

I might be able to assist

Should also check your insurance because some insurance will allow a roommate, some say you need the landlord policy even with a roommate.

I do not even know where they are coming from. 

ACH payments by their nature take a few days to know if it actually clears (you can know faster for credit card payments). 7-10 days I'm guessing is something like this:2-3 business days Tenant -> Zillow2-3 business days Zillow -> LandlordSo in summary, you'd almost surely know within a couple days if the tenant sends a bogus payment, even if you don't get it into your bank account until later.

If you went with the 'delayed financing' then you could recoup even more than 75% of the initial purchase price along with some rehab funds if that is something you are looking to do with the property.If you go cash on both the purchase and the rehab, then you could go with a refinance either on the unseasoned cost.

-you likely won't cash flow at all when you refinance, and you might even be negative.