I hire a property management company to take care of all the management side of our properties. 

I've read in a book that Real Estate Investment in Japan is often referred to as a "Scientific Investment" because it can be managed with profitability that is close to the simulation of earnings based on prior calculations of yields.

Talk to brokers local investors and property managers.

At 4 it's getting complicated, and thinking of 10+ makes me angry in advance.How do you manage having internet service at multiple locations?  

She did sign a rental agreement via AirBNB and my property manager.

What do you do if your tenant is 2-3 days late on the rent?What do you do if he is one week late? Do you always charge late fees or for a good tenant you will not charge? 

I am looking at out of state rentals right now, just doing research, and I was wondering if it was possible to manage an out of state rental property by yourself instead of hiring a property manager.

I also feel I could manage it myself.

I own & manage 27+ STR & MTR.  

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases.