Not your circus, not your Monkeys comes to mind. Have they consulted an engineer to design something that will do the job on the correct scale? Its my experience of wood shops that there is always combustible materials piled throughout the work area. If the place can afford the new expensive system it would lead me to believe that they are only getting busier and the dust production will increase along with the hazard.
I would put it back to the operator to have the system engineered. I have seen stand alone trailers that are parked beside the building and the collection system is integrated into the trailer along with the suppression system. Just a thought, if its a trailer it may get by site plan.