Y'know ? I preserve foods in Kilner jars all year long, and I did buy the Ball canning book from Lakeland a couple of years ago, but the height thing just did not in any way relate
We're on islands, with a very maritime climate and some fairly high hills. Most of us live in the fertile lowlands though, so here I'm at just about 60m above sea level, and I wasn't joking about never thinking about stewing beans up the hill.
Your plateaus (our Grampians were, once, a veeeery long time ago) are a different world entirely. Have you thought maybe about the insulated carrier box idea ? Bring the beans up to the boil, as soon as you set camp, and then put the potful into the box and set it aside until you're ready to cook ? You could do all that in the pressure cooker.
Having said all that, if making the beans is such an effort at height, why not cook them at home and bag them in mylar bags. Seal them and poach sterilise and they'll keep long enough for your trip. The term to google for information on that is
Retort canning
and it's used to make ready to eat meals. It needs forethought and care, but it will work for cooked meals and doesn't need refridgerated or frozen.
Best of luck with it
M