I realize we’d probably want to bring in a real estate attorney, but I’m assuming there are models in place that are probably well-established for such a partnership that I know nothing about.

Eliminate debt, establish a budget, and save.

Also, in regards to a per diem, I'd like to be a bit more optimistic that I can establish the right checks and balances to ensure that the contractor is not skipping corners.

Eliminate debt, establish a budget, and save.

But before that you need to establish that you purchased it with an investment intent. 

If you want to establish a long term relationship with someone who lives eats and sleeps creative financing and loan products - I recommend getting in touch with a well-versed broker who manage the relationship and introduce you to competitive products in the market.

LLC's separate your personal assets from your investments and offer you protection from lawsuits related to your property, they can help to establish a more professional image if you plan to expand, and they provide some flexibility on how you are taxed.There are some drawbacks, included fees and administrative work, but it's ultimately best to consider speaking with a CPA to determine the best option for you. 

Eliminate debt, establish a budget, and save.

Or should we just establish our LLC and get financing through a DSCR lender? 

If it’s verbal, they’ll need to document any prior communication or payment records to establish the relationship.If the PM is completely unresponsive, they may want to send a formal written demand for communication and payments via certified mail.