Parking Lots?

I have measured and had certified some routes that use a parking lot. The concern is laying out and documenting the route. If you can measure to some easily defined pivot points that you can describe on your map and then measure the shortest possible route I think you should be okay.

We've had courses certified that used parking lots. The route through the lot is marked with cones. We mark the locations of cones with PK nails and show them on the map.

I think you can use the lines painted in the parking lots to good advantage. When feasible you can specify that the course must go around all the painted spaces. But sometimes there may be a space or two that you really need to cut through on an angle in order to avoid an awkward sharp turn-- in that case you need to sketch the route in a detail on your map. (Well chances are you need to sketch the parking lot no matter what, to avoid confusion.)
PK nails are also a good solution too.

Bob, your (in)famous tale of eyeballing a rerouting of the Marine Corps Marathon course through a parking lot water station while the race was underway is one of the great tales of course measurement.

Agreed, JIm. How many of us could pull this off? Bob was a real hero in the running world around these parts when the word got out about what happened at Marine Corps that year.