For a food cozie I sometimes use my toque.  Being careful not to get (a lot of) food on it.

I do most of my own dehydrating.  With the heat loss while waiting to re-hydrate I've switched to pre-hydrate.  At some point in the day I'll use a container with a good seal & add 1/2 - 3/4 the water necessary to re-hydrate.  Dump the mostly re-hydrated stuff in a pot with a little more water and by the time it boils it's good to eat.