If the objective is to increase the percentage/overall number of fish over 12 inches without causing a fuss....
I would allow anglers to keep whatever size fish they want. To some extent. I’d also do away with personal limits and make a boat limit. For example
10 fish under 12 inches and 10 fish over 12 inches per boat. Doesn’t matter how many people or how few people. One boat cannot take more than 10 fish per day over 12 inches and no more than 10 fish under 12 inches. The maximum amount of crappie per boat is 20 fish.
I honestly think this would tick some folks off but I do believe it would accomplish the objectives