They simply do Fannie, Freddie, FHA, VA, and USDA loans.

Nor would I pay retail for a property with that low proforma return even though I like PR.  

If you have cash, you could pay off the underlying loan2.

If you pay more, you won't meet your metrics and will probably have negative cashflow and/or equity.You may have to make 10, 20 or even 100 offers to get one accepted at the price that meets your numbers.This is what all investors did BEFORE the Great Real Estate Crash of 2008-2010.

There were lease violations disrespecting the other neighbor's leased space and harassing the other neighbor and they smoked in the property against lease, lied about conversations, has made up stories about plumbing issues that plumbers couldn't find causes to, tried to get a dehumidifier and force me to pay, accused me on two different occasions very agressively in regards to the heat/electric service.

And I would love some passive income or at least someone to pay my mortgage until we can pay it off maybe.

I would keep the deposit unless I am able to rebook the dates and then I would only make her pay the difference for any unbooked nights. 

But this was an awesome opportunity for me because this is my first living situation where I will be on my own (and getting used to paying a rent/mortgage) but this will put my overall mortgage on a 400k house at roughly $2000 a month for the first year!

That means it takes forever to pay off the mortgage meaning you're paying a mountain of interest. 

I don't see them showing up or paying any of the back rent that's due to become current if they wanted to stay.