I was going to also suggest Tiger Muskie as anthropic did, but I'm feeling like your somewhat shallow depth would be more of a concern for survival over cold winters vs. survival over warm summers in Wisconsin. I think 10' depth is plenty for survival during a winter with the understanding that you are in Southern WI.
Are you doing any feeding? If so, bullheads do tend to gather when feed is thrown, and if they do, you might have some luck using a cast net several times a week.
Removal of as many of the 'trash' or 'rough' fish as you can is a good thing towards getting better sized fish.
Stocking adult bluegill may be a good idea too.
Don't forget about Hybrid Striped Bass also. They may help with some of the juvenile rough fish.
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