We always use a Bakepacker.  It is essentially an aluminum circle with an aluminum grid inside the cirlcle about 1" tall.  It fits inside a pot, fill water to top of the grid and bring it to a boil.  We mix up the brownies in a plastic bag and lay it on the grid.  Moist, delicious browines in about 20 minutes.  They also make great muffins for breakfast.  Its an esstial on all our trips.

if you have msr brand stoves, throw the brownie mix in a fryin pan and put a lid on it.......  then use the heat screen to keep the pan off the stove and its direct heat, setting the pan on top of it while it is circled around your stove....... 

sometimes it's tricky, especially if you have a heavy fryin pan, but if your pan is wide enough, it will sit 4 or 5 in. off the flame and you will get a much better and more even cook than right on the flame........  this also works for pizza dough or any other breads/ baked goods......  you might need to flip them after some time, so make sure they aren't runny......  oh yeah, and if it isn't a non-stick pan, make sure you use a lil pam or butter or sumpin, or it will be a disaster......

Actually the new technique we tried was to put a rock on the fire grate, place the brownies in a pan on the rock, then cover all that with the big cook pot.  The theory was the inside of the pot would get hot from the rising heat and the rock would protect the brownies from the direct heat of the fire.

It did not work.  The pot never got very hot so we ended cooking the brownies for 3 hours.  To make matters worse, we over cooked them (they probably were done after ONLY 2.5 hours) but the result was brownie jerky.

I like your idea.  I guess it is basically the same principle, using the water to protect the brownies from direct heat.

I noticed you were trying a new technique for baking brownies.  How did it turn out?  We have a pretty good technique.  On our trips we use store bought brownie mix, mix it up according to instructions and then put the mix in a turkey bag.  The turkey bag is then put in a pot of boiling water to cook.  The brownies fluff up right inside of the bag.  Works pretty slick but of course the brownies must be spooned out.

See my (You need to Login or Register to view media files and links) web page for some great recipes and for a 120,000 calorie menu for 4 people for an 11-day trip.  (Credit for all content goes to my wife).