The monitoring sounds is usually a means to isolate where the problem is but it seems that is not your purpose.   

From an asset protection perspective, it is important to note that an LLC is a very efficient legal tool to hold and manage investment real estate and to isolate the risk it generates.

Because this business is isolating.

None of my properties are so isolated that I ever feel threatened doing this.

Think isolated towns that are still a hub for rural communities, have a decent medical base, a college or two or three or military nearby. 

Just out of curiousity why would someone choose this model over a short term rental that is isolated by itself (privacy) or a hotel? 

Having never filed any state tax return before, I guess state tax return forms don’t exist in isolation but are filed together with the federal return, with various info in the federal return passing into the state return?

Your only option would be a pressure test to try to isolate the issue For the past 27+ years the cash or financed have been together in one catagory: "Cash or other financing not involving FHA". 

As mentioned, if this the situation is dire  (too stressful) after a couple of years and in many situations (not just isolated ones) maybe think about outsourcing management.

The property looks like a decent location and is isolated from neighbors.