This is my tried and true method for skin-on salmon filets: Brown paper grocery bag, carefully fileted into two, with each portion being larger than the filets. Set each filet skin side down onto paper. Trim excess to about 2" around each filet. Plop on hot grill. Cook until center flakes with fork. remove paper and filet from grill, set on cookie sheet or similar. Use a long knife to get between the skin and flesh at the tail end. Hold onto skin and bag, run knife along skin. The skin should be nice and stuck to the paper. Takes a lot of the fat with it. Discard. Sit. Eat.