how about flood cooling the same that is on most cnc mills
all you would need is a tub for the router to sit in with a drain to the coolant tank (eg. like a cut up 20 lt container) and a pump (I have used a 1000lt/hour pond pump with a head of 2.5 meters and some 1/2" irragation tube and smaller tube for the directional hose ) it pumps great for my Taig cnc mill plenty of flow would keep the dust down and would be easier to dispose of when the coolant is no good