I'm not sure I would buy a dehydrator right off the bat. A lot of people use an oven set on 'warm" with the door cracked open a bit. You can also get a lot of lightweight food from the supermarket, reducing weight and bulk by repackaging. I sometimes supplement with freeze-dried foods which are reasonably healthy. Like anything else, don't consume them exclusively for long periods.

If you really get into back country cooking, one would make sense.