"I'd want to experiment with cold water rehydration at home before being stuck on a trip with unpalatable (or unchewable) food."

I second that emotion.

My limited experiments (sadly, on-trail out of necessity) with this hasn't worked out well. It depends on how you do it and what foods you do it with. In general I think that taking your average dehydrated meal (a la Mountain House) or a grocery store side dish (rice or noodle based) isn't going to be very palatable.

What does work for me is mixing up dehydrated mashed potatos cold.

I also like dehydrated refried beans. Some will do the same thing you talk about: have a dedicated container to rehydrate them over a couple of hours as they hike. I don't do this, as I don't want to carry the water weight (that's not available to drink) and then have that container to have to clean. So it doesn't rehydrate as well for me, doing it sort of "on the spot", but well enough for me.

But while I've eaten a lot of cold meals on backpacking trips, I nevertheless DON'T have much experience at trying to rehydrate random backpacking meals without hot water. I'm not optimistic, but there might be particular meals and/or techniques with which I'm unfamiliar.

For me, the only point in doing so would be if my only resupply options are that sort of thing. It's why I do carry a stove sometimes, to have a wider range of things I can buy at a limited store, but with creativity and flexibility it's almost always do-able, even buying several days worth of food at a gas station mini-mart.
Brian Lewis