I know FHA has a strict criteria when deciding if they will loan on a property.

In your situation, since it's been going on a while, it would be hard to start implementing strict rental policies, but in the future, I would strongly suggest.For now, I would get the person out as nicely, but as quickly as possible, if you don't trust them, which it sounds like.

Will you be occupying (house hacking,) or is this strictly an investment property? 

I made wild guesses about the taxes, insurance, water/sewer.Also, NYC has pretty strict rent regulation.

Where they are hard is that they come with a more strict appraisal, and for a seller who knows that they are more likely to accept an offer that is using a conventional loan with a less strict appraisal.  

Seller financing deals are most available when interest rates a very high, because few borrowers qualify for loans, or when lending criteria becomes very strict, for the same reason.

Saw that one come up yesterday and wish I had the funds to buy strictly on principle that sub $100k PPU is rare!

A big reason is state laws around lending; no matter what the reason, or who the borrower is, there are some strict laws around 1-4 unit residential property loans.

And its strictly a design intent and not a thermodynamic breezeway.

Hey @Shannon Ludlow,Strictly buy and hold although I may try a flip in the future.