If you can distract them with a powerful vehicle to draw their fire, move in a nearby Chrono Legionnaire and simply chrono the entire structure away. This deals neatly with the problem of the building itself, as well as all of the units inside it. Each has its own use and each is worth taking. These structures always start out neutral, so when you find these on the map, take them, guard them, and use them. Just get em near a captured Hospital and they will heal back to complete health.
Derricks are a source of income.
These are a great way to supplement your income. Make sure that, when you take them, you have the units to defend them. If you lose em, the money flow stops. This structure can repair any of your damaged vehicles free of charge. Even better, once captured, an outpost obtains a small gun that it uses to defend itself against minor threats.