Here is a weird situation...
Just for grins, where does the county GIS place the property lines. Someone else had got to be wondering that too.
One of the first little chores I was assigned at my new job in our fair city was a problem with drainage on a side street. Storm drainage running down off the main road was causing flooding problems with a house at the low point about 500' from the intersection. Fixing the problem was going to be a multi-million dollar undertaking. My first reaction was to suggest that buying the house and demolishing it was going to be the cheapest way to go, and this in the knowledge that a houses in that area start at over $500k for a flooded out fixer upper.
It didn't take too long for me to realize that the road, although paved and marked with the usual street signs, and shown on street maps as a numbered street, wasn't a dedicated road at all. Which I communicated.
One of the young engineers put a fair bit of time into preliminary investigations, including speaking with all the affected owners, and sketching out a preliminary plan and cost estimate. A meeting was called. His cost was pushing $3 million before allowing for right of way acquisition. One of the attendees was an engineer who has been with the city for 20+ years. He made a few suggestions about engineering issues with the proposal, but was otherwise restrained.
This fellow later told me in private that the exact same problem, same street, had been assigned to him back when he was the young new guy at the city 20 years ago. The owners wanted the gravel/dirt driveway that then existed made into a public street and paved. That required that storm drainage issues be addressed. He had almost lined up all the owners up that street to pay for the fix, when the city's public works operations manager got a new paving machine, and was Jones-ing for a little something to try it out on. He layed asphalt on what had been a gravel/dirt driveway in a day, thereby undercutting my man's negotiating leverage with the neighborhood, and his project fizzled.
Turning back to today's problem - the fact that the road was not dedicated right of way allowed the engineering manager to say "not my circus, not my monkeys". Nevertheless, there remains several million dollars of real estate up that street without documented access.
Why on earth would you want to do that? You have completed your survey. You are not their consultant, realtor or title company.