The US when testing zero length launch integrated the system onto a road mobile trailer so it could be towed anywhere and used as a point defense fighter anywhere on land (terrain permitting)
All the Soviet zero length launch systems I've seen have been rather more... experimental in nature, a static ramp for testing purposes quickly abandoned.
Am I right about that? If so it seems to be a less attractive tactical proposition if you can't spawn a zero length launch system anywhere on the map like you could potentially do with an F-100 or F-104