"so does a coffee bean in the wrong environment. Basically, the bean should be stored air and light tight in room temps (I'm only assuming room temp) and that can't quite happen on the trail. So from a taste perspective (and maybe preservation) are we gaining anything by not pre-grinding and packaging for even the longer trips. Will the whole bean, improperly cared for, hold up better than the ground, over time, such that we would consider packing a grinder of any weight?"
Er... yes and no. In all modes of storage whole coffee beans will last longer and retain taste better than ground.
Realize, Coffee Beans travel a long way to get to you, and not in climate controlled semi-trailers. Also, bags of whole beans can sit on the shelf in the store for a very long time.
Rule of thumb, all other things being equal a chemical reaction will proceed approximately twice as fast with every 10 deg F temp rise. This would seem to support your initial query, however realize that, realistically, you're only looking at maybe a 10-20 deg F temp rise as compared to 'normal storage conditions' during the hottest part of the summer. Typically the inside of your pack stays somewhat cooler than the outdoors.
Also, the degradation of whole bean coffee is nearly all due to oxidation. There is relatively little free oxygen in a sealed container so there is a limit to how much oxidation is capable of happening. Now, a less full container will have more oxygen and, theoretically, could spoil the coffee quicker (that's why the preferred container of choice is those roll top bags). However, this is more theory than practicality.
Shoot, if you have a whole-bean grinder with a hopper at home it typically violates all the above: exposed to light (easier to see when to refill), not air tight, significant free space for more oxygen (on average it's probably half full), in the kitchen (one of the warmer places in your house). However, most hoppers hold half a pound to a pound and a half of beans, and no one (or I should say only the most persnickety) complains when it takes a week or two to go through a hopper.
Now, contrast this with the reasons Ground Coffee spoils quicker.
1) Surface Area.
The surface area for Ground Coffee is orders of magnitude greater than Whole Bean. This causes any oxidation to proceed at a MUCH more rapid pace. Oxidation rate will increase along with surface area.
Note: this surface area is why we brew with ground rather than whole beans, and why fine grinds brew 'faster' than coarse grinds.
2) More sensitive surface area.
As with any heat treated food, the exterior surface area is going to me more resilient than the interior areas. Heat / roasting is going to 'seal' the skin to some degree.
3) Escape of volatile aromatics.
From my understanding, this is the worst part of pre-grinding your coffee. Much of the tasty goodness of coffee comes from compound that can evaporate (volatilize) fairly easily. Pre-grinding exposes these goodies to the atmosphere. In whole bean coffee they are trapped inside do to the opposites of 1) and 2).
In short, you'll be ready for a resupply on a grinder this small before you experience any noticeable degradation in your whole bean coffee. Unless of course you're a super-coffee-snob, in which case the weight penalty of the grinder and a special container (one of those roll top bags inside a large ziploc bag) is not going to matter to you as you would rather not hike than hike with pre-ground coffee.
Basically, this is a brilliant little find for those who like fresher coffee.