I want to learn more about BRRRR, Turn-key investing among others. 

That being said, we carry a receipt book in our LL filebox (the box that travels with us with keys, LL forms, etc -- we have learned to take it with us whenever we go near the rentals)  and are happy to handwrite a receipt at any time.

Glad to have you on board!

The other is turn key, has 1 side rented for $400/mo, I plan on having a tenant in it shortly after closing at the end of this month.

In the past I have sent rental contracts to a potential renter who was stationed in Korea, did a walk through of the property via FB messenger video chat, ran background checks with TransUnions Smart move, collected security deposit via PayPal and emailed the tenant the code to the lock box that had the key.

@Charles Adams welcome to the boards!

Your OP said saving money was key due to your overages.

If you'd found this guy two or three months out there would be a few easy creative finance solutions involving above board vanilla 30YF Fannie stuff. 

I figured someone had a key and let themselves in. 

When you put a lot of time, money and sweat into a place it can be hard to hand the keys over to someone else, even a tenant.