His methods are unsafe and unwise.

And maybe it's not all or nothing for a given method, sometimes a combination of various financing tools is what wins.

I am sure there are people who did it, even on this forum I saw posts by multiple users who claimed that they were successful doing this method.

So while I greatly appreciate all the different methods of making money with real estate and even more impressed with all the hustlers that grind here in this community, I just need properties that I can get at a good deal that cash flow and appreciate while minimizing the trouble commonly associated with real estate. 

Which is to say any attempts beyond the method of communication in the profile are likely to end up convincing the landlord you and your friend would be a pain in the butt as tenants. 

I recommend an electronic payment method.

Other than the fact if they tried to make every owner of their own home put in a 10k to 20k sprinkler system, they'd all get voted out of office - every last one of them.

It's crucial to consult with a tax professional who understands the nuances of your situation to determine the most appropriate and cost-effective method for your tax filings.

I see you mentioned the BRRR method, here's a nice breakdown of it here on Bigger Pockets.   

Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.