I haven't yet tried this, but I've read that you can rehydrate dried food without heating if you allow more time. This probably involves adding the water to your dinner in the morning, which means you're carrying the extra water all day. Of course that would cancel out most of the weight savings, which is why I haven't tried it.
I'd want to experiment with cold water rehydration at home before being stuck on a trip with unpalatable (or unchewable) food.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey