The inclusion of a space blanket/heatsheet is not a bad idea. If a person "goes down" and it is not advisable to move them, a hasty shade could be rigged. Just a thought.
Excellent point, MoBOB. A hasty shelter could be invaluable, if you can't move a victim and have to wait for help. Shade from the sun, cover from the rain or wind...
I while I don't think we need to make our FAKs full on PSKs, I like mine to be minimally stand alone, including a little shelter, water and fire. When doing something like canoeing, for example, I put mine in a cargo pocket in my pants, so I have it in the event of a bailout. Having a few essentials could be a lifesaver if I'm away from the rest of my gear.
I guess it goes back to the bigger picture of what else the missionaries will be carrying, and how.