Here, see the map.ini in the single player mission:
Firebases that can move - Cncmaps Map Editing Forums
It has firebases that can move like hovercraft and that contain stinger soldiers.
You cannot use spawning else they will not be inside the firebase. Instead use an OCL to load them (see overlord gattling OCL).
If you want them to load over and over again when they are shot by snipers etc, use OCLUpdate (see the supply dropzone) and set the interval to 30 seconds to match the normal stinger site respawning time. However OCLUpdate will remove the command buttons (like for supply dropzone).