For the record, Xpanding Man is ditching the A27M for a shapeways 3d-printed mount. It's the better practical answer for him.
But to answer the original question here for anyone coming across the thread, the heavy A27M could actually work quite well in a single shock mount. A stiff enough suspension is required to support the increased weight, but the increased inertial mass of the bar+mics will actually serve to better isolate the system from outside vibration.
All shock mount suspensions work on the basic principle of inertial-mass balanced against spring-rate. The spring has to be just stiff enough to keep the mass from sagging too much in the mount, yet compliant enough to allow the sprung-mass to be vibrationally decoupled from the mount. That's easier to achieve across a broader frequency range with a larger mass being suspended.
Think about how much easier it is to get light-weight thing moving or vibrating even when it is suspended, versus a heavy thing.