Challenger is a great SAR aircraft.
There are a number of military's that use them for surveillance and SAR.
Robust engines designed for relatively lower level flights (Same as a A10 Warthog)
In flight baggage door, actually designed to be opened in flight. There is apparently a bomb removal procedure that means dispatching it out of the rear door.
The only thing I would suggest is that the 605 would have been a better option for the aircraft as in 12 years time the 604 will be a pretty old ship.