TJ, I think the removable small fish cover would be the way to go (cedars). With vegetation growing in the pond basin, more SMB would be trapped and you'd have to hand fish them out after the water was down. Remove the cover before opening the drain, or have the trees going across the pond like Cody said. If the branches/cover just hangs into the water, as the water receeds, they will flop out of the cover to stay in the water. Not so much if the cover is laying on the pond bottom.
I'd fill the pond asap in the spring if you are leaving it dry over the winter and put in a buttload of sorted FHM to keep the babies from eating each other.
How do you get the adults out post spawn?
Did you notice much scale loss on the fish you collected?
