I and my extended family flat out LOVE my Salmon Planked on a grill. In the last year or so, after reading a scientific reccommendation, I use a light coat of mayonaise on both sides of the filet, then use GFS's Salmon Rub (their own brand, "Trade East Salmon Rub"). In the past, I used a light coat of olive oil. The scientific paper claimed greater moistness in the grilled salmon. It is absolutely on point!
So, now, I put a light coat of mayonaise on the fish on both sides, then apply the rub just on the meat side. I then plank it just like I have in the past (full chimney of lit coals spread evenly over the charcoal grate on my Performer, all vents open, heat the food side of the plank for two minutes by the clock, flip the plank and, with the lid on, leave the plank heat until it starts smoking (5-7 minutes). Then, I open the lid, place the salmon on the plank or planks, close the lid monitoring it closely). You learn to eyeball the filet - some steelhead filets will cook properly in 7.5", some thick salmon filets will take 20 minutes. You want to pull the salmon when it JUST begins to flake. That is done enough, and you retain as much moisture as possible. I use a rather large, commercial, spatula, and slip it between the skin and flesh, removing just the flesh for serving. I immediately remove the plank and put it in water to stop the smoking.
It is re-usable. After it cools, just scrape the bits off under running water, let it dry and place it in a paper bag until next time. You can generally get two or three times when grilling fish. When it is past it's time, just break up the remainder for smoke wood.
FWIW
Dale53