If anyone have any advice on how to find motivated buyers I would greatly appreciate it.

Something simple and achievable in short order

One of my favorite RE books (that wasn't already in your list) that was digestible and informative:The House Hacking Strategy: How to Use Your Home to Achieve Financial Freedom -- Craig Curelop

I sell with dual license in KS and MO, but want to do more.HiA great start is putting a deadline to that goal you gave yourself.We can assist by holding you accountable , encouraging you along the way.To hold that many properties, equity is your target....Alot of free equity.You can get that as you help motivated sellers solve their problems too 

However, I'd like to vocalize my opinion on here and it can just be taken with a grain of salt:My intention here is not to guide you to any decision but to suggest considering if you can achieve your goals via other methods and consider the opportunity cost of both doing and not doing something.

What do you achieve by paying extra principal? 

Look for motivated sellers and distressed properties.

What strategies have you used to motivate tenants to quit the lease and move on?

What are you looking to achieve?

I like to tell folks to have some type of goal in mind - in other words - what is it you are looking to achieve through investing - of course the cash flow and appreciation - but quantify that a bit - is this to replace your active income, is this to diversify your portfolio, to hedge against inflation, etc - by having a specific focus it makes it a bit easier to figure out which direction to go, what types of investments to point out to you and get you closer to what it is you are trying to achieve.