To de-treble your spinners, use some cutting pliers or a bolt cutter to cut the treble eye, remove the treble, and replace with a smallish siwash hook (which is easily closed around the split ring with a pair of pliers). You may want to look up some redside shiner pics, to get a feel for what color combinations might work best. Sounds like a silver blade over a red body might work....

For trout of the gawdy proportions mentioned, I would step up to 6-lb. leaders, especially for spin fishing.