The key here is you have 2 powerful and hard to get units (I don't think you can buy brother Devon or grave digger at all right now) that both have multiple drones to attract the firepower - after sending a merc into the side (great strategy thanks!). Trying these bases without units with drones is MUCH harder. If you don't have these units - keep searching videos and good luck.... (Canons with admonishers could work...?)