I don't like the full foil wrap - takes a lot of the grill flavor away in my experience.
SO, I make a makeshift pan out of heavy duty foil. Doubled up, and with rolled edges to make a mini baking pan that is just bigger than the fillets.
I smear a tiny bit of olive oil on the foil before I put the fish on (skin side down).
Season with garlic powder, seasoned salt, coarse pepper and a bit of chili powder.
Grill until done - no flipping needed. It almost always slides right off the oiled foil with a spatula. Moist, tender and tons of flavor without fall apart risk or risk of falling through the grates.