Thank you very much for those. I'm looking into them. Both look very promising. Pretty certain that the film I have in mind was wartime. 'Heaven Knows' looks suspiciously like 'Mother Goose'. I wonder which came first? 'Hell in the Pacific' looks like it ought to be a great movie even if it's not what I'm after. If in either one, Robt Mitchum or Lee Marvin reveal a real diy/macgyver bent while repurposing machinery off of a boat to set up their digs on the island, you will have helped me solve the mystery movie.
I'll get back here if, after watching, they aren't exactly what I'm after.
Working my way through the 'survival' genre and its sub genres. War survival, prison/camp survival, tropical island, arctic, deep woods, under ground, trapped in the city, desert/outback, outer space, etc. Horror survival just leaves me bored, don't know why. I experience movies like "Saw" as a form of bad comedy more than anything else, no matter how brilliantly written/acted/directed. At the other extreme, I feel exactly the same way about organized religion, so that may explain quite a bit.
One of my favorite survival films is "Walkabout". Two children endure the Aus outback after being abandoned by their father. Little of the grueling, nail biting, drama usually associated with survival tales, but a beautifully conceived story. An amazing little movie.
It's usually what is developing inside of the character's heads, more than most of the action taking place around them, that attracts me to this type of film.
I came across a Polish production called "In Desert and Wilderness" that had been described similarly. Two children of an aristocratic family are kidnapped in Africa, escape their captors, and must survive the wild elements. But it's based on a children's book originally and it shows, unfortunately (unless you're 12 and under). It's much more "disneyish" with exaggerated stereotypes of character all the way through and mostly predictable hijinks and made-for-tv plot progression along the way.