Davis,
Got an idea for you to make it as close to the same as possible.
Setup two drop shot rigs (or perch rigs). On one rod, put your minnow on the bottom hook and your plastics on the top hook. On the other rig, reverse it. Put the minnow on the top and the plastic on the bottom.
This will have each rod having the same offering and will let you know if it is depth that they are after or the bait they are after. You could do this first with dead minnows on each rig then do it with live minnows on each rig.
I have OCD "Obsessive Crappie Disorder"