Made great salmon fillets last weekend over the campfire.
Prepare marinade before you leave in a large ziplock and use frozen salmon fillets (I get mine from Sam's club). On the day you're going to cook them, take them out of the freezer and put in the marinade. I grilled them about 10 min each side over a cherry wood fire, using a pan with holes drilled in it over the grate. The people camping with us said it was the best Salmon they had ever eaten.
Marinade: 1/4 cup apple juice, 1/4 cup real maple syrup, 2 tbl soy sauce, died shallots and garlic to taste.