My buddy Todd used to do "planked trout". He'd take the fresh trout, clean it out, cut off the head, then cut the body so that he could "butterfly" it so it could be opened up, kinda flat. He'd get a piece of applewood, green, and split it in half. Then he'd take the trout and lay it skin side down on the flat side of the applewood. He'd take a nail, and tack down the four corners of the fish, then remove the nail, and replace it with a sliver of applewood, (the nail made the hole for the "peg" but would taint the fish if used to cook),..., so the fish was open, flesh side up, and fastened to the freshly cut side of the applewood log by applewood pegs. Then he'd prop it up facing the fire, like a crude reflector, and let it bake.
I like to take a couple of green branches, apple, maple, hickory will do, and make two "grills" by removing the bark. Then I fasten one end of each branch into a loop, and criss cross several smaller, barked twigs to make a "grill" or a "racket". (I hope this make sense). I lay the whole cleaned fish on top of one of the grills, then I put the other grill on top of the fish, and tie the two grills together where the handles start, and at the top of the hoops, tight! The fish is then sandwiched, with a grill on each side. I prop it over the fire, not too close, and let it roast. Turning is easy and instant, (if the setup is tight..., if not you dump the fish into the fire when turning) and it's done when the top or dorsal fin comes loose with a gentle tug of the fingers. I like this as a no utensil cooking demonstration for Boy Scouts and other kids.
LD