Moreover, a standard buy-out/eviction would be costly/time consuming since they've been in the unit for roughly 8 years.

Being that she’s on the mortgage, does she have any leverage to pursue any legal action be put back on the deed, and consequently refinance and get the house from me?

Start the talking and documentation so if you decide to take further action you have a nice paper trail.  

When risk is shared, all parties are incentivized to take action that is in the best interest of reaching a successful conclusion.

And pick who you like best, so has a good action plan, and who cares about you (by answering your calls and reachable).

I found that most of what I consume can be recycled, so I got the biggest can for that.

I’m a 20 y/o college student from Oklahoma, and within this past year I’ve consumed real estate knowledge like my life depended on it.

In the event that the tenant still doesn't leave, what is the next course of action that I can take?

It's possible there are some buyer actions needed in that other form of 1031 I'm not familiar with?

While I agree with you that it 'might' not be the best business practice, I'm genuinely curious-- which law(s) you are referring to that would be violated by the actions you mentioned above?