The appraisal came in 20% below the total investment I'd made on that property.9 months later and I had a major issue that ended up in a $20,000 insurance claim (I managed to get $15,000 of it back). 

But they forced you to use their management company, took 50%, and you couldn’t use the unit more than 2 or 4 weeks per year.

I approximated 7% for property management, 10% for maintenence, and 0% for CapEx.

I would completely agree with the idea of putting at least some of the funds in an interest bearing account if you were self managing and not a licensed agent. 

I also feel I could manage it myself.

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 do not have a PM, but actively manage my STR. 

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? 

The key for me was having the right teams in place (realtor/lender/property manager) to help me find / fund and stabilize the properties. 

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