As is: as long as you do not "touch" a pickup zone with your wheels, its NOT shown on the map. But its visible. See the following pictures:
As my scout can see "there is framing (wood)" why dont you allow a scout to show that on the map as soon as he can SEE something (rendered). Would make scouts having at least a BIT of a purpose when you compare that with small (4x4) trucks as the Actaeon or the Warthog.