Start with your regular grinds, but in a cauldron and with 2 cups less water than you would for a right now cuppa.
Brew. (I brew mine with cane sugar and nothing else. Do you.)
Remove from fire.
Stir in 2 cups of ice to cool and stir until all ice is melted.
Brew should be lukewarmish to the touch, but not hot.
Ladle into 1 gallon freezer bags.
Place bags into ice chest/cooler and layer dry ice on top until covered and close the cooler.
Forget about it for at least 72 hours. Then another 36.
Now you have instant coffee crystals for your camping/fishing trip.