I'm going to echo the suggestion on talking to Doug and for your FAKs, the folks at AMK, but just to toss the ball around...

You have SAR assets available- Civilian? Military? Contract? Whos? How long will it take for them spool up? Are you over water, or over land only? How long is your typical flight, and are you ever out of communication with the airports?

I would think the first thing is the individual kit, on each person. The PSP or the SOL from AMK or one of the better small kits from BCB (but go through it with a fine tooth comb), a good pocket knife, and water.

For the aircraft, you're big thing will be signals. The sat phone/gps combo, and/or a PLB per aircraft, based on the checkered performance of ELTs that's we've seen recently. Mirrors, whistles, signal panels, strobes to show exactly where you are. Flares, smoke bombs, not so fond of.

Fire extinguisher.

Water. Obviously.

Shelter. I don't know that part of the world, so other than a sun shade, I'm not sure.

A good first aid kit.