Case in point: I had envisioned the route to wind up through the Duck Hill area, and link to the dirt roads on the north side of Carson City. Looking at the satellite imagery and maps indicated this would be a feasible route. On Saturday, after parking my butt at the Top & Drop of the Washoe(s) 5-Mile(ish) trail race, I had the time to do a quick reconnoiter of the path. Lo and behold: a locked gate. That would make things difficult.
Back to the drawing board (ok, the GM and GE toolset) to establish a new path. I think I have one, but, methinks I'd better hie out there and make sure this one doesn't have gates. Or tank traps. Or aliens lying in wait for racers. But that last one could change between mapping and race day. I guess the participants are on their own when it comes to alien abduction.