I'm sympathetic to the reflector oven but prefer the JMO (jello mold oven) for same reasons.  It works on a gas stove or over a fire, and is lighter.

Also a big fan of solar shower.  It's that last item I think about leaving out and then toss into pack at last minute.

Paperbacks, binoculars, star chart, and playing cards - the other items on my not absolutely necessary list.