[AndyBare]

If each bot as a front and back intake, and can also outtake the boulder, you can have one bot navigate outer works, and sit over the defenses, one bot perched in the courtyard for shooting, with a bumper in the plane of the outer works, and one bot that takes a boulder and feeds it to the next which feeds it to the next. Essentially, 2 bots could be completely stationary, forming a chain, while one moves back and forth to and fro the feeding station.
Also, the 2 stationary bots can't be defended against, per rule G43 I believe. I'm on my phone though.

Thoughts?