I'd rather not take the legal route but need some commitment that they'll pay the outstanding amount shortly.  

If there is an outstanding balance when we sell the quad, would that just be rectified by the title company? 

Quote from @Pat Lulewicz: Have you every considered renegotiating your rates with her because those are ridiculously high across the board. 50% for a renewal is high-way robbery and should probably the first one to go.

If you have a good location and unit and can be an outstanding host, you can have income that exceeds LTR by enough to justify the effort.  

We finally got someone to schedule a zoom with us and thought things were moving forward and then got on the zoom and it was just them telling us they’ll follow up the same day with more outstanding details in an email (that was a week ago and the email never came- we have sent follow up emails asking about it and they are all unanswered) We have our first payment coming up and are now frantically searching for another solution because 1.)

Being close to the highway has netted me quick stays but I also have some weekly rentals for workers traveling and working at a job site in the area.

Also, provide outstanding guest service.  

Conveniently Located Near Shopping, Major Highways, and Downtown.

It does not take much math skills to realize that without an extraction of value that the cash flow would be outstanding.  

You can get a general idea of what a property is worth, by looking at Redfin.com SOLDS, that sold in the last 90 days, that are the same square feet plus or minus 10%, that have the same number of baths and bedrooms, that were built within 10 years of one another, same condition, same style of house, not across a major highway, a river, a railroad track, etc, or to can spend $500 and have an appraiser do that for you.But, it isn't like buying a candy bar.