What's your control loop bandwidth? Do you want the loop to suppress the disturbance at 180 Hz? If so, then you already have a marginal control loop design. Getting control at 20% of your sampling frequency will be just possible without the latency of an AA filter in the loop. Using a 6th order one will introduce a huge group delay around 180 Hz, and make it impossible to stablise your loop.
Even in the 'control the 180 Hz' case, you don't need the AA filter to be down by 500 Hz, you only need it down by 820 Hz, the alias frequency of 180 Hz.
Why have you chosen -40 dB for the stopband depth? It sounds like a PIDOMAPIDOOMA.
I would recommend building the loop with a single RC pole at 200 Hz or so, and seeing if you can get the loop stable. Then see if it meets your noise and other requirements. Only if it doesn't should you try to increase the AA filter order.
Do remember that your control loop itself acts as a lowpass filter.
In the event that the loop bandwidth is only enough for controlling your 2Hz disturbance, then it all becomes enormously simpler.
To do a proper design of the loop, including any AA filtering that's required, you need to specify what attenuations are needed for the various disturbances.