X2 = a slurry of ice and water with salt mixed in. The salt will help drop the ice temp below freezing.
coarse rock salt - much like the ice cream churn system. I have never thought of the mix ratio.
I guess it would be one cup of rock salt per 8 pound bag of ice with one gallon of water ??????
Some parts of the country use only table salt, some only Kosher salt, some only Rock Salt. If you have never
done this before, it might be a good idea to experiment with your cooler BEFORE you go on your trip.
Find a safe place to drain off some of the excess salt water. Keep in mind that it does kill vegetation.
You must keep a slurry or slush going..... if you use only ice and rock salt, the ice will
most definitely become one frozen mass and will be hard to work with.
Different methods for the fish are used around the country. Some remove the innards, some don't.
some completely clean and bag the meat, some don't. I guess it is the way we
learned from others in different parts of the country.
Personally, I do not clean the fish away from home. I ice it down whole like Lugo said
with the ice/salt/water slurry and clean them when I get home. and I pour the salt water around weeds.
Good Luck on your trip !!!