The load will vary with conditions. In AZ in the summer, you will want water - lots of water. two pounds is only about a quart, which will not be enough, although way better than nothing. Some means of two way comms would be useful, so that return trips could supply pertinent supplies. Very challenging topic.

Don't expect your victim to be signaling, or really doing much of anything,at least if my experience is representative. Probably the victim is relatively or completely inexperienced, likely either dehydrated (maybe even thirsty), confused, disoriented, or injured/impaired in many possible ways. They are likely to be inert, and very likely lying beneath whatever cover the area affords....

I find this thread interesting, because, frankly, it could be pertinent to me. I am definitely not as young as I used to be, and my range is increasingly limited. But I could do a reasonably competent job of watching a screen, especially in areas I know fairly well. There are lots of geezers like me out there who would form a fairly effective resource.