I measured a course last year that was almost linear with a common S / F and turnarounds at each end. The RD noted you should be able to start and finish anywhere on the course without changing the distance run. This was important because Morristown, Tennessee is restricting the number of courses they allow due the effort required to "design" police coverage and road closures. This way, someone can set up a venue anywhere along the course and legitimately claim certification. Obviously, the Mile marks will be off. Link to that map:
Johnson City, Tennessee is doing the same thing. The course below is on the list as Standard Course #2.
The question is: Could you claim that this is a certified 5 km course if you stared and finished at the same place on the course using the common S / F as a turnaround point?
And I realize there will be public safety "timing" issues if you do that.