How about a limit set up like duck hunting (you waterfowlers will understand this) You are allowed a total number of ducks, but certain species are limited in that total number. For example, Mille Lacs could have a 4 fish limt. Of those 4 fish, only one could be 18-22″ and only one over 28″.
Example: a person could have 3 fish under 18 inches and one between 18-22″. Or they could have 2 fish under 18 “, one between 18-22″ and one over 28”.
You could play with these numbers numerous ways. But I think the general idea would allow a harvest of fish of all sizes and not hammer on certain size classes. Plus it would give anglers a good chance of at least bringing home a fish or two for dinner.