I wouldn’t be afraid the breakdown the situation by making trolling passes from your normal 16-20 all the way down to under 5 feet. If the shoreline you are fishing is a gravely rubble mix then I would cut right to the chase and get under 10 feet as I believe the fish would most certainly go shallow.
I would cruise in that 15-20 foot range and see what you can mark. If it’s relatively little then it would be safe to assume the fish have pushed up shallower, and thus focus your attention there.
Like others have said a great bait is the Shallow Shad rap or a Jointed Shallow Shad Rap for a little more action for under say 5 or 6 feet of water. Depending on the forage base, I wouldn’t hesitate to go with a yellow perch, or step it up to something a little brighter like Fire Tiger.
The next level of depth, around 10 feet, which I would most likely attack with a Husky Jerk or a Deep Scatter Rap.
Stepping down to around 15 feet you’re looking into that #10 Down Deep Husky Jerk, which is actually a good bait to cover a wider range of water depths.
Then to the 20 foot range which could be tackled with leadcore but for the sake of being easy a #9 Deep Tail Dancer will get you in that 20 foot range.
Good Luck! Let us know how you do!