I notice that the 328s have the ability to drop stuff though a certified open door. Dropping beacons, rafts, pumps etc from a CL604 with an open door will be a whole new ballgame if at all. I see only one door on a 604 and it is forward of the wing and right in the vacuum envelope of the engines.
Other possibility is to have an aft cargo certified 'bomb bay' for SAR products but I suspect this would be prohibitively expensive to certify unless it has already been done.