Judging by the description of where you're fishing, I'm not surprised that they are hugging the bottom. Perch will use the entire water column provided there is virtually no current and there is weed cover. Add current and no cover - they'll be on the bottom.
Given your description of the river, I'd still go with a neutral buoyancy deceiver style but I'd rig up with a heavy, sinking leader on a floating line plus I'd run a single BB splitshot 6" above the fly. This will hold the fly head down, just above the bottom. the neutral buoyancy fly will hold its position in the current, gently moving from side to side. A quick stip and it'll dart up and forward, then settle down again. It'll move far more naturally than a clouser. The rapid jerks will interest the pike and bass by pushing lots of water. While it settles, mends can be made up and downstream to change direction. When the fly doesn't sink, it gives you the luxury of time.